Probably the thing with Fighting Vipers 2 and others Model 3 ports is exactly that, those are games built around the complex tech of Model 3, so at the time they were not capable to convert the game 100% faithfully, bc DC has an entire different architecture. And about the DOA 2 numbers, yes, they absolutely prove VF4 could be somewhat handled by DC. Could DOA 2 Engine be modified to create a....DC VF 4?
While what you say might be true about being super different ,he posted more examples( Virtua fighter 3 rooftop stage, Virtua striker 2 stadium) that genki had more detailed models for their model 3 ports despite how looked down upon they were. Overall it seems they out performed am2 in porting from the same machine, again what happened to that famed prowess that an outside dev could out do them on their own machine and tools? It's just a very curious and mysterious case. At its best judging from downgraded Dreamcast examples model 3 probably runs no better/ higher than doa2 on the DC tops, shouldnt first party devs done better at these ports? Especially genki getting much closer ( by Virtua striker 2 it's super close to the model 3 except for a few things) compared to am2?