it's apparently easier on just about any trainer to use a lower gear at a given power level. I was having trouble with my kickr dropping out of erg mode using trainerroad, and they recommended that approach.

I would go with the newer trainer. They apparently change internals on a whim, which is a software developer's nightmare. I'm going to guess they prioritize software development time on the currently shipping product. Yes, this is not exactly a ringing endorsement of the product. When I bought mine I thought my problems were all due to using android to talk to it, but the Apple apps were just as broken, if the internets are to be believed. I have to say that right now everything is working fine, and I should probably just be happy about that, but it still leaves a bad taste.