I don't know if rollers necessarily improve your handling ina lot of real-world situations. I know, it seems counterintuitive, since it's definitely harder to ride rollers than to ride on road, but the areas where bike handling is critical on the road is cornering (NO help from rollers here - in fact, rollers only train you to ride as upright as possible), fast swerves to avoid missed potholes/debris (obviously avoid this as much as possible in group rides, but the inevitable does occur) , and timely braking with possible skid handling. Rollers don't assist with any of these.

What rollers DO help you on, is a smooth acceleration. If you can accelerate up to high speeds on rollers, you'll have a nice smooth acceleration. The roadies drafting you will thank you for it, but if you're planning to drop them all on a hard accel, again, rollers won't help you with that either. (On my rollers, if I do such a fast acceleration, I'll fly off the front of the rollers.)

I've got both rollers and a CycleOps Fluid2 trainer, and I've ridden both fairly hard, although admittedly, the rollers get way too sktechy on those 110% interval sets for me to be comfortable using them.

The rollers are marginally more interesting on their own than the trainer, which is definitely boring as all heck if you have no feedback. HOwever, get a rear wheel speed sensor to get your speed (power correlates with speed on the Cycleops and KK due to the realistic power curve) and a set of Spinervals DVDs, and you'll be hammering like no other. I don't have time to be bored on the trainer - I'm too busy suffering beyond belief and keeping my speed up on those spinervals!

I honestly don't think I've gained anything from using my rollers this past year other than a smooth acceleration that I knew how to do anyway even before using them. I've given them a pretty fair shake, and can ride them to a hard workout no problem, but there's no way in heck that I'm going to ride them as hard as my trainer. Anyone who says you can ride your rollers as hard hasn't gone hard enough on their trainer - I go so hard I'd probably keel over if not secured by the trainer. Even if I were a roller master, that type of effort wouldn't be possible on rollers without wiping out.