What happens to the audio if you play the loop SLOWER than it was recorded at? Are there 'gaps' between the audio, as the slices get moved apart, or does the engine time-stretch them?

Most of the professional loop tools (Acid, Live, REX, Apple Loops, etc.) will time stretch the ends of the samples, to allow for slowing down the loop without creating holes in the sound. Does any arranger (apart from MS) do this?