Depends on your use case. If you want to play ROMs and can live with software emulation, something like a Retroid would probably be better. If you want to play physical cartridges, a modded GBA should do the job pretty too.
If you bought the Pocket for the expansion adapters and still have GB/C/A games you want to play, hold your preorder.
Honestly, from the discussions I've seen, most people don't really care about FPGA emulation. The Pocket is the new shiny thing that lots of folks don't own right now and honestly don't need.
If you buy any product, ask yourself if you are happy to use it in its release state. Buying anything for a potential jailbreak is just naive.