I've been clipping off quite a lot of HQ bases (and also grenadier plastics bases).
The key to success is to use small clippers, doing small clips. Work your way around the edges, and remember SMALL clips. If you try to take off a whole chunk at once you might end up with a plastic clipping projectile firmly lodged in your cornea. It's usually much quicker to do three or four small clips than to do two large, as you don't have to take as much care. As soon as you need to strain and apply pressure to the clipper, you're clipping off too much in one go.
I keep the mini cupped in my hand too, to avoid projectiles. Careful with the hand flab though, don't want to get that caught in the clippers. =)
Once the model is free you can trim down the plastic clogs a bit, to make them less elevated. I use clippers here too.
