For me, Stages V2 have been performing really well for most than a year now: consitant, reliable, light and reasonably affordable. It's maybe not 100% accurate, but if consitant, that's OK to track own progress and do workouts based on power. I own a Drivo since last week, and seems Stages reads low on power, but being left side only, its possible my left - right balance is not 50 - 50 %, so nothing I can fault Stages for
The consistent but not accurate argument again, eh? no, it does matter.
Say your real L/R balance is 55/45. For simplicity sake, lets assume an FTP of 100 Watts, 55W left, 45 watts right Stages assumes 50/50, so it would read 55 watts left foot and multiply it by two- telling you your FTP is 110 W. Stages will OVER estimate your power by 10%. If you are using power to design your workouts- you'd be 10% over your required power all the time. would your intervals be effective then? Worse, if you're riding a time trial and pacing using power- you'd be going out 10% too hard, a recipe for disaster.
Now say you were 45/55 L/R balance. Assuming an FTP of 100Watts again, Stages now UNDER estimates your power at 90 watts. again, all your workouts would then be 10% below what you'd really need to hit, you'd be too conservative for your pacing. Considering stages is +/- 2% accurate you could be looking at as much of a 12% error.
granted, if your L/R balance is lower- say 42/58, you'd get less error, but your L/R can drift when you are fatigued, and it's been pretty much shown that MOST folks are not 50/50. Stages is also highly inaccurate for Short sprint intervals. if you ride track, A stages is not going to give you good data.
For most people, a stages may be 'good enough', but unless you know your true L/R balance you won't really ever know. If you're already spending $700 odd on a stages, why spend so much money on an imperfect product?