I’m in the camp that has PowerMatch turned off. I moved from a KK Road with virtual power, to same with a 4iiii Left only, to an Elite Direto. With PowerMatch on, ERG mode felt pretty erratic, as if three parties – me, the 4iiii, and the trainer – were wrestling each other. Now TR gets power from the Direto’s optical sensor only, and that has calmed things down.
So what about outside rides compared to inside? I was hoping for a reasonable correlation between the 4iiii and Direto, so I did a bunch of inside rides with TR power data coming from the Direto, and with my Edge 520 recording the 4iiii. I then exported these and used DC Rainmaker’s Analyzer to compare them. I found that in my working range the 4iiii reads consistently 10% higher. As it happens, the 4iiii app gives you the ability to offset the watts up or down. So I applied a .9 correction, and it stays at that setting (unless I modify it again). Occasionally I do a test indoor and run it through the Analyzer again. They agree enough for me. I don’t know which is closer to an objective standard.
Here is a link to Rainmaker’s handy tool: https://www.dcrainmaker.com/analyzer
I think a few uses are free, and then you kick in a few bucks if you want unlimited access. Takes a while to figure out the wrinkles, but it’s very useful for comparing how different devices see the same workout.
The Direto seems to me sturdy, consistent, and likely durable – as hardware. I’d almost bet that some of the frustrations with Elite stuff could be addressed with firmware updates – but so far they seem pretty cagey about when if ever that will happen. I second the suggestion to use the small chainring in front for ERG mode. I use whatever cog in back gives the straightest chain line.