He’s right. If you want to practice compositing in a safe photoshop environment AE is the way to go. It’s as close as a motion image application can get to photoshop in look and feel. The problem is… I feel like that’s its greatest draw back (besides lacking many features I need). Personally I find the AE inteface horribly awkward (and I started off using AE before buying a copy of combustion) and assbackwards. They’ve improved the interface tremendously in 7 so if you do go that route, I wouldn’t recommend anything less than 7. It also has amazing features like gasp F-Curves. If I have to animate a circle using speed curves one more time, a macintosh G5 is going to fly.
I wouldn’t be to concerned though about the learning curve on Combustion. It’s completely unlike any application you’ve ever used, but it doesn’t really take much time to get the hang of it. Also I’ve found it was an excellent stepping stone to node based compositors like Shake, Nuke and Fusion.
Also combustion has a very nice graphically oriented interface. The color corrector is a perfect example of this. Instead of having to move hundreds of little sliders, just about every single interface thatcan gives you a graphical expression to its purpose will.