It's much more difficult to use, but the clip tool is better than the carve tool for a few reasons.
a) It won't screw up your map like with the carve tool.
b) You can plan out how your block will be seperated.
c) It's easy to use if you use good logic and spacial awareness.
I disagree a bit.
It's very easy to use, you just have to spend a few minutes figuring it out.
Clicking the clip icon multiple times gives different options (ie:delete left half - red side, delete right half, don't delete either half - both sides white).
Or using shift-x instead of clicking icon.
You click one point (use as large a grid size as possible), click second point. choose option (see above), hit enter.
a) it CAN screw up brush, maybe not entire map, if not cut on grid (brushes will be shifted to spot hammer thinks is best, can have weird results)
It's also nice because you can clip as many brushes as you have selected if you need to.
Say you have 3 brushes over a doorway, they are all different sizes, but you want an even strip of trim all the way across.
You can make 2 cuts (top and bottom of trim) and make trim across all three brushes at once evenly.