About the only "downside" I can see in putting an indivision AGA into a CD32 is the fact that these older systems sometimes look BETTER on TV sets or monitors with fewer pixels than they do on newer monitors. The low pixel counts soften the edges a bit where games look "blocky" on modern monitors IMHO.
If you are in the states and are looking for a solution for playing PAL games (like 99% of CD32 games are), I would recommend picking up a used multisystem TV set. I grabbed one off of Craigslist for $40 locally and it has SCART and does PAL/NTSC.