879m, i mean that is a pretty long vert, but i see your point (havent even checked for regen up there).
I believe B2 should be T5 because it does take a long time to make the bonus.
Also, why is 4starters just t2? There are some parts in the map that aren't t2, i mean there is speedpogo involved, which definitely isn't t2. I believe some courses should be T3.