Having used both extensively, I honestly wouldn't even bother with the rollers, seriously.

Everyone hoo-haas bout the "TECHNIQUE" of rollers, but that's the biggest oversold piece of hype, ever. seriously. If you think you'll become a superior bike handler bike riding rollers - get what - nope. Won't happen. All rollers do is smooth out your acceleration. They do NOTHING for awareness, cornering, stopping, etc. You even have to ride a bit unnaturally on regular rollers because you have to be so still - any little jerk, including standing up briskly, will throw you off the front. Having ridden now seriously for 4 years, I rarely ride outdoors in the stock-still position I do on the rollers.

I also will include that last year, I rode the rollers a lot due to being forced indoors due to scheduling before the outdoor season started, and I honestly felt a lot worse outdoors than had I just stayed on the trainer. This was definitelyk because the rollers train you (force you) to ride dead-straight upright. Even a slight body tilt, such as on a turn, is unacceptable on a rollers - you'll go off the side. Went to outdoor riding, and was shocked at how poor I was at even moderate downhill curves, as I was so locked into riding deadbolt upright.

My acceleration was smooth, but that totally doesn't matter when the pack takes off as well. If anything, you better be ready for hard, brisk accels when the outdoor season hammerfest starts, since that's how the group will try to drop you if you're riding with fast guys on a hammerhead ride. They're not going to gently accelerate to keep you there - they'll hit it hard on the go, and you'll put up over 700 watts trying to close the immediate gap.

I also honestly believe that if you are so sloppy on the road that you cannot hold a straight line, you'll have no chance on the rollers. Your best bet in that case is not to force yourself onto the rollers, but to ride outdoors until you CAN hold a line, and then get on the rollers, and rollers are 3-4x more hard to hold a straight line, if not 5-6x harder. Reality though, is in real world, how hard is it to hold a dead line once you're past basic competence? You will NEVER ride on a road surface as slippy as a roller surface. I also hear the argument that you can adjust faster if you get bumped, and while that may be true, getting bumped is far different than roller riding - you get better at recovering from bumps by practicing being bumped.

This is my experience, and others may differ, but I spent over 100 hours in the last 2 years on my rollers trying to 'prove' they were better than my trainer, and even after doing all the techniques (one hand, one leg, standing, no hands), my conclusion was clearly: trainer >>>> rollers, mainly because the technique aspect of rollers is so over-rated in my experience.

Have said this before, but there was only ONE roller-technique that is extremely useful to practice, and that is looking back over your shoulder for cars while riding. If you haven't done this on rollers, you'll be shocked at how far laterally you will veer, which is extremely dangerous in a tight paceline or even in general. Once you master this on rollers, you'll wonder how you even survived doing it with cars just 3 feet off your shoulder in the past.