For me in VICE, this resulted in a bug: “Please insert game diskette” after going north, which did not happen when true drive emulation is on. [perhaps we should make a new topic about this particular game?]. For me, a better method to speed up the game is BEFORE turning on warp-mode, you go to file->Monitor and type: > +650 +127 (including the “>”-sign). Then you won’t have problems with space when running at warp speed. Even more speed is achieved by disabling the unused sound playback. I reach about 1200% speed this way without a problematic space key.
EDIT: I made a topic for this over here: Artful Deceit - emulator settings