Rollers vs Trainer

[7rider]

You can look at it either way....

ROLLERS
Pros - mimics riding on the road, works on your balance, works on coordination, smoothing out pedal strokes

Cons - Balance!!!!!, can't really take your attention away, can't really sit up or look around too much, some cheaper ones don't have much resistance

I would say your con (balance) for rollers is actually a plus (as you already mentioned). Nothing works to keep you still and efficient on your bike as rollers. They are unforgiving of bad technique, but once you get it down, they improve your riding as no trainer can. And what's the point of riding indoors if not to have some positive benefit, eh? Cardio benes being equal (for added resistance, just shift up), the rollers will make you a better rider. And, FWIW, my DH can ride no-hands, take his shirt off, wipe down, and take a drink of water while spinning away on his rollers. I am no-where near that...but some day...maybe I'll be able to drink without stopping!
By the way...I do my Spinerval DVDs all the time while riding rollers. I don't stand up when they stand (DH does), but shift up an do everything else just fine....