You findings is not that different. It just seems like maybe SemanticMirage did the test with the repeater without mechanical reloader and the test with the great crossbow with?
Also Haphazarduk if it is possible to do a test of a great crossbow with around 20 in BAB and 0, 15 and 30 in ranged alacrity with no doubleshot i will update my page accordingly - with Rapid reload and rapid shot.
in this post
https://www.ddo.com/forums/showthread.php/341522 he had a time of 55 seconds on 19 BAB with RR and RS. This was for a heavy repeater. This seems to be a bit off when comparing to your 42 seconds for 99 bolts with a light repeater and BAB 11 unless this result was with mechanical reloader?