Yes.
It’s actually more beneficial for me for Zwift, which is the only way I can tolerate low-intensity rides. The system-provided resistance variation makes it tolerable. Makes hills much more normal.
Erg mode is real useful though. There can be a lot of screwing around with what gear you need to hit a power than you can now ignore. It also personally helps me from quitting or seriously missing power targets. With enough mental effort, both of those are fixable, but that’s costly for me.
Gotta ask, aren’t there a ton of issues with all of the smart trainers? DD or not, it seems a lot of frustrated owners. Kinda scared me away from taking the plunge.
I have owned two smart trainers…I havent had an issue with either. Currently have the Tacx Neo 2 which I am very happy to be using.
If you like watching movies, or reading books, yes. Training is more enjoyable.
I can’t comment on the Flux.
It’s like everything, only the disgruntled make their voice heard so you only hear one side of the story 
Here is my n=1. I was on a crappy nashbar fluid trainer for 4 years, moved to the kk road machine. That was a huge improvement. After 2 years on the Kk I had a chance to grab a saris h3 for a good deal. I do 90% of my riding on the trainer. 6 weeks ago I got a saris (formerly cyclops) H3 and it has been a game changer for me. I have been riding with power for 5 years or so and the introduction of erg mode has lightened so much cognitive load for me there has to be benefit. I am now able to focus on spinning at the desired cadence, focusing on good pedal and breathing form , etc.
In my experience, if you plan on doing a lot of training indoors, the smart trainer is totally worth it.
That may be true but the volume of complaints seem higher on some trainers versus others. I think it’s worth paying attention to before making a purchase decision.
My issue with all these $1000+ trainers is that they are practically unrepairable. There are no exploded parts diagram or spare parts available. If I bought one I’d try to at least buy it at a place like REI who has a generous return privilege and I’d want to use a credit card that extends the warranty if possible. If it works well for 2 years it will probably continue to work well for a long while.
I like the trainers with ERG mode because they force you to do the work so you really can’t quit, and if you ease up the cadence to try and sneak a break it just gets even harder to turn. I also feel like after spending time on a trainer that holds the power for me, I can hold power myself better since I’m used to doing long steady intervals, though your mileage may vary there.
I am also about to invest in direct drive smart trainer after a few years on dumb trainer + power meter.
Things I will not miss:
I was comfortable with holding steady watts and switching gears. The main reason for the switch would be quiet time for my family and fewer vibrations for my neighbours.
A few thoughts:
ERG mode is to resistance mode as Electronic shifting is to Mechanical shifting.
Will it make your ride better? Yes, probably.
Will you still get faster/have “fun”/reap all intended workout benefits without it? Yes.
If you don’t have a power meter on your bike, that is a far better spend than a smart trainer, IMO.
I have the Tacx Flux S, and have been happy with it. But, for what it’s worth, I still split ERG and resistance about 50/50.
I’ve found that I get too used to ERG and when I get outside and want to ride at a consistent power it’s very difficult. Found this out in a TT I trained for. Nailed indoor workouts, but holding my target watts during the race was a huge cognitive load since I really had to focus on adjusting cadence and changing gears, which I had not been practicing indoors. Spikes and valleys + cognitive load ended up harming my performance, which could have probably been managed by practicing in resistance mode a bit more.
Erg will make your workout different versus doing it outside. Depending on the workout Erg can allow you to multitask. But like texting and driving in car, does multitasking makes my driving “better?” Clearly Erg creates an opportunity to take a time efficient workout (inside on trainer) and make it even more time efficient (get other stuff done).
I think there’s a lot of great discussion above. I think it’s good that people have it; there seems to be this idea amongst some people that a smart trainer is something that you just HAVE to have. Like some stated above, I do think that my Kickr has value, I do find it ‘better’ overall than my Kurt, and I do typically enjoy what erg mode brings overall, but the other side is that you can get ripping strong on a used Kurt with an Inride sensor for $140 off Craigslist too.