The only computer to pop up ejected CDs like toast! That makes it worth a look as far as I'm concerned.
I can't speak to performance relative to the SAM, but in general MorphOS is quite zippy. The machine will definitely feel much faster under MorphOS than MacOS(X). Caveat is that if it does have the GeForce installed you're out of luck since MorphOS doesn't support it (or didn't last I checked, which admittedly was a while ago). Give the MorphOS demo/live CD a try and see what you think. At most, you'll be out the cost of a CD-R.
I find MorphOS's compatibility with system-friendly 68K software to be better (e.g., less crash-prone) than OS4's on my A1XE. It also supports classic WarpOS PPC software and (I think) PowerUp as well, so you'll be able to run a lot. For native software, there's of course Aminet, plus MorphOS-Storage, and developers hosting things on their own sites. I think MorphZone is still the main hub for announcements not found elsewhere and, as I discovered the other day, their Library/Documentation section is really quite good for learning nuances of the platform.
And yes, if you can get your A2000's drive connected to the machine (IDE-->USB?) it should mount right up.
