Yes, wait until the drivers are available (you will also benefit of lower prizes). There are 3 generations of radeons on sale (I guess I will have forgotten some models, but these are the most common ones):
Radeon1: VE,LE,7000, 7200, 7500, 7500AIW...
Radeon2:8500, 8500PRO, 9000, 9000PRO,8500AIW...
Radeon3:9700, 9500, 9700PRO (these 2 will be on sale pretty soon if they aren't yet)
The Radeon1 is a DirectX7 GPU, so AFAIK it doesn't make many things apart from T&L
The Radeon2 is a DirectX8.1 GPU, it includes the Radeon1 functions and adds some interesting ones like TruForm (a technology that creates additional polygons to give a smoother model, for example the CPU may calculate the polygons of an hexagon and the GPU may create a nearly perfect circle), that was the most impressive feature I can remember, they are also quite fast even with anisotrophic filters and FSAA...
Radeon3 is first card that fully supports DirectX9 (no, parhelia doesn't allow fpu operations with its gpu and the chip developed by 3DLabs also didn't have full hardware DX9 support), at last GPUs can do complex operations, loops like you may code in C, etc... they are a CPU in a graphic card but with a 256 bits bus at 500Mhz(DDR), so it's way faster than using the CPU.
Now, the problem is the support of these technologies in AmigaOS. By the moment (correct me if I am wrong) Warp3D doesn't support even T&L, which is a basic feature of the first generation of GPUs. We will have to wait until Warp3D-NOVA is finished to use the GPUs properly... so buying the latest model may not worth it if NOVA takes too much time to appear, only when it supports the latest generation. And then probably you will be able to buy a better model compared to that you may have bought initially. So my advice would be waiting until the card you want is supported and don't buy anything not supported because by the time it is supported you may buy it cheaper.
The G550 is quite slow compared to any Radeon, so don't worry about speed. The image quality of ATIs is quite decent also. The Voodoo3 is well supported, I would use it until a Radeon driver is released.
