The advantage of training with Powercranks is that you maximize your time on the bike. For example, riding one hour on PC feels like spending the double on the normal bike, expecially at the beginning when your muscle are still learning the new pedalling style.
That helps in this days, where I live the weather is getting worse: so cold and rainy that it's impossible to go on the road.
So I used the opportunity to ride on PC on a hometrainer.
45' consecutives minutes, averaging 70 rpm just below 200W
with 2x3' SFR at 50 rpm and 300 W. On my legs I've been feeling a great training stimulus and I can be satisfied with it.
I don't usually like to spend time on the hometrainer but I know that time on the PC has greater value and it's easier for your mind to deal with it.