I really want to get a SGFX to be able to play Daimakaimura, too
Just so you know, the game is available on other systems like SS, PS, PS2, and PSP. I'm not a G&G fan, but I'm pretty sure all of those ports are as good, or better, than the SGX version, so buying a SGX for G&G would be like buying a PCE for SFII (pointless, although fun is where you find it, I suppose).
I don't have a SGX, but I have every intention of getting one some day. What I'm not going to do is try to fool myself into thinking that there is any rational reason for it. I just want an odd and huge-ass PC Engine with six mediocre exclusives.