I disagree. I wouldn’t compare data between PM’s of even same brand model if you want consistency. But to each his own. If we should learn anything from people like GPLama I feel like it’s that PM’s are not 100% perfect tools. Yes, there are more reliable models out there and won’t hurt your training comparing data but this would not be something I would suggest someone who’s not interested in comparing 5 PM’s to eachother and finding out which one’s perfect etc.
25 watt difference is outrageous and wouldn’t say common. You might be way off balance. It’s not mine or most people’s experience. Blaming single sided PM’s for this would be inaccurate info.
Also, if you think smart trainers are 100% correct, you would be wrong again. I had a kickr consistently 30 watts off (not joking). and my Neo 2T is around 10-15 watts lower than known good sources.
Sorry don’t mean to be that guy. I’ve changed more PM’s than I care to count at this point. Have seen good ones, bad ones and everything in between. There’s no such thing as single sided bad, double sided good. Smart trainer accurate, single sided bad. Generalizations pretty much end up wrong in this topic because the data is dependent on so many different things.