Hello everyone. I happen to have a K6_2 400Mhz machine, a Compaq, that has this SiS GPU integrated on an AGP bus. I think it is 2X AGP. I have 8MB of my main memory shared with the GPU.
For 2D games, this GPU works GREAT in DOS. For 3D, it is not amazing. I am hooked up to a 640x480 monitor (27"), so I do not game on this PC in higher resolutions than that. Anything mode 13h runs fantastic. I can get BUILD Engine games to run quite well on this machine! Duke Nukem 3D runs at a constant high framerate at 640x480 with High detail and shadows enabled and the full screen. Great in DOS and Windows. Redneck Rampage is a bit more resource hungry, but it runs quite well on this PC. I wouldn't try to play Quake III! There's no way that this machine will handle that! And Capcom games sometimes boot to a black screen. Mega Man X3 works though. Jazz 1 and 2 run just fine. Alien Rampage works great. Commander Keen Episode 4 works great. DOS compatibility so far is fantastic. It has run every DOS game that I have thrown at it except for Battle Chess.
I do not have an ATI Rage II+, but if you check the compatibility list, that card clearly sucks for DOS. It just cannot play so many of the treasured staples. The SiS has very few problems. It performs great for anything up to and including BUILD Engine games. If you want to go newer than Quake 2, I would look to Geforce and Radeon.
The SiS is a good DOS card.