Are there any disadvantages to the solar version at all?
I live in Denmark, so solar charging really wouldn’t give much of a beenfit, but currently the solar is cheaper than the non-solar version here, so if they are otherwise identical, I might as well get it (and use it as an excuse to travel to somewhere with sun…)
No idea why they’d price the solar cheaper than the non solar… get on it! 
They probably bought some at the distributors and can’t sell them because everybody thinks like me, that they won’t need them in Denmark. 
Yes the screen is not as bright
Plus side is you get solar and with double the storage, world maps
You can find it for cheaper, there are some 20% off coupons every now and then. Check out Biketiresdirect.
To the original question, I went from the 530 to 1040 Solar and have zero regrets. It’s amazing. I wanted a bigger screen and tried the Karoo 2 but it just wasn’t up to par with features and the battery life was terrible. So I picked up the 1040 and couldn’t be happier. With the Solar, I charge it like once a month. The extra screen space is awesome and makes the data fields bigger, but I use the map screen the most so it’s nice to have a bigger map and a couple data fields. The big thing I was afraid of was the touch screen not working well but it’s been flawless.
I did order it. Got 20% through my health insurance. But ordered it through garmin and their processing time is 2-3 weeks. I did consider the hammerhead as that screen size almost seems like the sweet spot. But I figured I wouldn’t be happy with the feature set and battery life. And also I’m used to garmin eco system
I just switched from a Karoo 2 to a 1040. I’ve only done a few shakedown rides on the new gravel bike I built, but it’s been good so far.
As for the Karoo 2, it has some genuinely excellent features (navigation and routeless Climber especially), but the negatives are just too much right now. But especially the battery life. I was tinkering with some settings on the Karoo in the morning before one of my major gravel events and turned up the brightness a bit while I was double-checking the route and tinkering with some settings (from my usual 35% up to 65%) to account for some major glare around the start area, then forgot to turn it back down.
I’d never had battery issues before, but that 30% bump in brightness meant that the Karoo ran out of power about 4 miles from the finish on a 70 mile event. Everything was clearly marked and I made it back just fine, but not capturing the whole race was infuriating. I put it up on Ebay a week later and bought the 1040 when I found a good deal. Having the battery life be so short that a 30% bump in display brightness reduced it from the usual 8 to less than 4.5 hours is just not acceptable. I shouldn’t have to pay that much attention to screen brightness that it could impact a single ride under 8 hours.
The Karoo 2 irked me when I accidentally zeroed out my power meter during a ride from their control center drop down while trying to get a sensor connected again. I was also a victim of the “if two things beep at once your Karoo 2 crashes and you lose your ride” issue. >_>
Just ordered a 1040. I think it was @WindWarrior who mentioned that he had some syncing issues with the x30 series that went away on the x40 series. With my 530, that’s one of my main complaints; that workouts, and especially courses, take forever to load. It can involve on/offing and force closing Connect on the iphone. If you had sync issues with your x30 Garmin, have you found those issues going away on a x40? Also, I got the 1040 because it was cheaper than the 840, but the 1040 doesn’t have the side buttons. I’m in a place where I wear gloves a lot. With the touch screen, is that going to be maddening? Finally, as a keen racer, is moving to a 1040 unacceptable? 
Went from 530 to 1040. Love it, would not go back. Arguably the only downside to the 1040 is the size for anything more techy than XC MTB.
I’ve had my 530 on an out front mount (Tarmac stem). I’m assuming the 1040 will fit in the same space? Is the syncing better on the 1040 than the 530 was?
Since buying the 840 about 6 months ago (April 15), I’ve had a handful of syncing issues (guesstimate). One or two required turning off 840 and turning it back on. Once or twice I tried some voodoo and toggled on airplane mode, toggled off, and launched Garmin Connect mobile. However it usually syncs immediately. Another thing to keep in mind is you have to answer all the questions (how much did you drink, eat, rate the RPE, and accept/reject auto-FTP updates if that comes up) and then tap the checkmark in upper corner before it will sync. That takes you to a summary screen, and then it will sync.
Tapping the checkmark on the summary screen will take you back to the home page, ready to start another ride. If like me you tap that while still slow rolling back to your garage, it will ask to start recording if you have auto-start enabled.
So the 840 Bluetooth in general has been really really solid, but not perfect. However as a heavy bluetooth user that has been true of other BT devices in the house for example my AirPods don’t always immediately switch if I’ve been on a computer call, stop the call, walk downstairs, and make a phone call. BT and cars can also be interesting, generally ‘just works’ but every once in a while the complexity that is BT rears its ugly head and either the car or phone get confused.
Sounds good. I’m not sure the ride upload on my 530 has ever been too problematic. It’s more the workouts or courses that can take forever.
Former Edge 530 user that made the jump to the 1040 Solar.
TLDR: never going back to the 530.
Endless Battery
Larger easier to see screen (53 years old and eyes to go with it)
Wasn’t a fan of a touch screen, but now it is so much quicker and easier to use
Options to use the phone to edit/change data fields/app/CIQ etc.
Mapping/routing is much better (quicker and easily readable).
Everyone with the 1040, go get the Garmin Edge Remote and lead your best lives.
I had no idea this device existed! I love the remote ability with my di2 bike, but on my mechanical gravel bike I miss the ability to change pages and hit the lap button during workouts easily. Anyone who has one of these have any feedback on it?
Managed to find a 1040 non-solar from a BF sale for less than 450€. 
Most likely will not take it into use during the winter, however. The old 530 is good enough for riding thru the winter on my mtb hardtail.
Mine was a similar price. Really hope the syncing is vastly improved 
Works great. great tactile feel even with gloves. swapping pages quick click to go to the right, hold down to go to the left. Never touch the screen unless you want to. Battery lasts forever (year+)