I dont think he JUST gave up.
I saw prototype ISA boards (probably just mock ups) at the 1998 WoA show in London. Along with the "inside out" PCI Amiga he was working on. The original designs used the Amiga chipset from CSG but they had just closed and stopped manufacturing them.
He also designed the WSICD32f (the CD32 floppy disk interface) currently being sold by Analogic on ebay.
By 2001, everyone from the Amiga professional community was dead or dying. Even Amiga format had come to an end.
BoXer had eaten a big hole in his pocket, probably didn't work well enough for release.
I think their development would have been greatly enhanced if they had all the BoXeR research to use with their designs though, rather than starting from scratch.
Possibly, but you are assuming that they actually made anything to put in the FPGA's. You have to consider the FPGA's on the boxer board were 1/10th (if not less) the size of the MiniMig FPGA, and even though he had two of them, they had far more to do than the MiniMig one. That might have been the stumbling block, the damn thing just wouldnt fit.