I use a dremel w/ a cut-off wheel to remove the rivets, grinding off the flared end of the rivet., Once the flared end of the rivet is ground off, I drive the rivet out, using a small punch and hammer. I also keep a damp rag nearby to cool the rivets as I grind them off...especially if you plan on re-using the plastics. The rivets get hot when you grind them, so cool them off w/ the wet rag so you don't melt the plastics. This is really important if you're removing ramp flap...you don't want to melt the ramp.
The problem I see with drilling the rivets out is, sometimes, the drill bit will bite into the rivets, causing them to spin which, in turn, mars/melts the playfield plastics.