I got the bepros recently (single sided) and v happy with them – easy to set-up, power seems reliable. Not really thought about battery life as an issue – they seems to last weeks so it’s not like a laptop or a phone, say, where it’s a critical parameter. Basically there seemed to be a strong concensus on the web that it’s a good, reliable product – researching it didn’t turn up many negative experiences.
It’s a look cleat only AFAIK – I think the vectors have some more options. I’m not much of a roadie, so am not arsed, but I can see how proper roadmen might have strong opinions on what cleat they want to use.
They do give me quite different readings inside and out, but I think this is a common phenomenon and not down to any particular power meter. It’s such a different form of riding.
The power I can sustain on a 10 min, eyeballs-out interval on the turbo is easier to hit outside on the road up a hill. Feels like the difference between being at the top of the threshold band and the bottom, roughly speaking.