I am super skeptical about Sega controllers.
Even the late release Sega 6-button controllers (by Majesco?, the one with the turbo function) were sub-par for me. That and the performance 6-button pads were good enough to get me started back in the day, but basically failed me after a year or 2.
The original Sega 6-button controller is great though and really set the bar for me; only being matched by the Saturn model 2 controllers.
Dreamcast D-pads were fine for me, actually. I have always liked how smooth they roll and was able to really improve my game with them playing Cap vs SNK. My only gripe was the 4 button layout for other fighting games that cater to 6 buttons. My most used one is getting a little TOO squishy on the right though

. Saturn converters save the day though

.
I may have to try that SNES buffalo controller, as the SNES was the only other system besides the big Sega 3 to really get the D-pad right for me (N64 is basically the same D-pad, but awkward shape for a digital controller, more for 3D gameplay). If they got the Buffalo close to quality, it would really be an asset to emulation, and a must have for a pi setup.
...wondering if USB Saturn adapters work on the pi...
...just another lost soul...