very interesting thing..
but i think most of the people know the "terrain" advantage but if want to say it is "terrain" why don't just say it is BLIND spot? i think it will more easy to understand. well sentinel has more advantange in mid lane :/ i also need some time to understand what you try to say -.-"

Sentinel side have more blind spot then scourge side, so when your Scourge side hero at river there, probably can't see the Sentinel side hero at the higher ground there, especially at night time.
erm quit hard to explain by word, just need to know that, 1 on 1 not only on deny and farming skill, who can play well with the blind spot, also have an advantage.
Try and play around with those blind spot, quit fun ^^
and yes, who at lower ground probably will have alot disadvantages.. who can control the creep well is lead him to win... v6.37 not hard to control, but the sohai 6.38b version, who know how to control the creep wave ?? the two stupid big car very disgusting -.-" hope new version will remove that !