I love Magic, but as Joska says, its no good for some programs, is no longer supported, can mess up the file system (occasionally), and will never be developed to support new improvements/compatibility.
Geneva could be an ideal basis for multitasking AES as it (a) would run on low end 68000's. (b) is low resource intensive, and (c) AFAIK does not effect latency or timings of which would be particularly useful in MIDI applications. I think also, there are some patches for MIDI software, and I just love on the Atari how the GEM system allows for its components, like AES to be compartmentalised. 3D buttons for example still rock my world, and I love in Magic how well a 8Mhz machine can work like a modern PC ... File copying in background, draggable windows that don't 'ghost', and it makes file operations so easy.
The Atari is longing for an up-to-date, non-unix based, simple but powerful AES that is not a resource hog, yet brings it into the league of what Classic Macs have been doing for years. With GCR on the 8Mhz machine, MAC OS runs better than the old classics, but the OS really shows what the ST is really capable of. ... For years, I used to use Classic Macs, and I always thought my humble ST was no where near as good ... And only recently realised it was more powerful all along (by about 3/4 of a MHz) and with higher resolution. However, the lack of hard-drive (I used M-Disk with 4MB) and lack of affordable alternative OS with multi-tasking really made life a pain. The other big pain was GDOS, in which I never actually got my printer (which cost more than the ST) to actually work properly.
What desktop shells are best to use with Geneva, that are lightweight?