Encryption does nothing anyway, the packet filters can see right through it. ( Im sure slingshot has Layer 7 ones too )
Even if they dont , they probably have encrypted traffic set as low priority or throttled.
Btw im on AYCE, and for those thinking about joining it, its alright, biggest issue is inconsistency. Had a spell of good speeds , then a few days ago now everything went crap after the PPP issues. Now the speeds * at least on the p2p speed graphs * are all over the place. In simple terms, looks like multiple mount everests on the graph.