Uh, i bought the single leg because I didnt have much $ at the time, still dont, I traded liquor for the quarq... but i do like consistency and stuff
^^This is great
I still have the single leg Stages that I bought in the summer of 2014 - First Gen. I was running a 2nd Gen Dura Ace Stages the past two years on my race bike and noticed the power to be between 10-20 watts lower than my old Stages. I calibrated both before every ride. Basically it just comes down to them being different systems. One might read a bit high or a bit low but what's important is that they are consistent.
Kind of a pain in the ass, but I would do testing on both bikes. My old Stages is on my trainer bike, so I would have indoor power numbers on that and outdoor on my DA Stages. I will have one of the new Quarq dZeros on my race bike this year so we will see how much of a difference there is.