help me out.

One came out for a console that died too early.

Absolutely, Positively, just about everything. MVC2 on the PS2 was easily one of the laziest, worst arcade ports ever translated over to the PS2. Sure, it's playable and all on PS2, but that's about it really. Audio is heavily downsampled, Visuals as are incredibly muddy. Loading times... altered hitboxes, slowdown, etc. The only reason the game sold for a hefty price in the used market was just because the game had a very short print run on the PS2 and Xbox.

Dreamcast MVC2 is as perfect as you can have outside of a NAOMI setup, simple as that. The game was made to be effortlessly ported onto the Dreamcast with arcade perfect results. It SO perfect that Capcom chose DC code for the MVC2 release on XBL and PSN.

My only quirk about the DC version of MVC2 is that the 6-button scheme has been downgraded to a 4-button control scheme. Would the DC arcade stick solve that problem?

Yes it would. The arcade stick is great . I never got into arcade sticks before but i use them all the time.
I was just thinking about doing this type of thread. I wanted to ask if since I own the dreamcast and have a lot of 2d fighters if I should go the dc route with the kof imports and CVS2 or just start going for the ps2 route.

I suspect the code for the DC and NAOMI is a lot more readable and easy to modify than PS2 code. The DC was supposed to be a nice platform to develop on, something that was NOT the case for the PS2.

How is MVC 2 on the original xbox?

It was good for me but the xbox controller still had that 4 button layout. Maybe if I used the street fighter arcade pad that came out it might have Breen better to play but I liked it.

I have that beastly Pelican Arcade Stick.

Getting a Total Control converter and using Sega Saturn pads is also an option if you want the 6-button control for a lot less money.