I've been playing GalCiv2 (and now DA) on a eVGA 7950 GX2 since October or so, with Hardware mouse OFF, and I've never had a lockup problem that could be traced to that option. I just noticed the post about this today so I decided to double-check things on my end.
I'll say right now that I'm not sure if I'm running in SLI during the sessions since I've never had a profile created for the game. Knowing that I made a savegame (relatively early in DA) to benchmark my fps from. At my normal settings: 1600*1200, 4x AA from in-game with gamma correction and super-transparency AA forced in the drivers, 16x AF forced through the drivers I was getting 70 fps. Closed it down, made a profile through nHancer and played around. I left all of the settings the same and turned on SLI. AFR and SFR made no difference and the load balancing graph doesn't work in GC2, so no luck there either. Either I'm running in SLI without the need for a game profile, or I never have been. I'm going to play around with compatability flags and a few more settings but at this point I'm not really worried about it either way since it runs just fine.

Edit: Well, crud. Forgot about the frame rate throttle and apparently GC2 forces V-sync (though I didn't see the option in the menu). I turned off the throttle and forced v-sync off, and now I
know SLI is working with it set to AFR globally and a few compatibility flags turned on since I was hitting 250+ fps. I'm also leaving hardware cursor OFF. I'll post back later with a final result....if I don't miss too many more obvious things.
Edit2: I gotta stop doing stuff like this when I'm tired. It makes no difference in my framerate if I have the driver set to AFR or Single and it doesn't care if I have a profile set up for DL&DA or not. With v-sync off I did verify that both GPUs were working and that mucking with the SLI settings didn't make a bit of difference. The exact spot I used to benchmark stayed at 180-185 fps through all the setting changes.
Final Verdict: I'm leaving everything like it was. The 72 fps cap that I'm forced to by v-sync is fine by me. Hardware cursor OFF has never given me a problem. Now for more DA.