Harry--Tortola is over all much quieter than SXM, that's for sure. Most islands are. Especially in October, as that is the height of hurricane season, and a good part of the clientele of the BVI are boaters.
With regard to flying there, in HIGH season, Winair goes to Tortola every day and most days there are two flights to Tortola, so you don't have to deal with Liat's BS..