I have the Velbon Sherpa Pro, which I think is the same as the 630, paired with the Markins Q3, for my 40D and 70-200 f4. I find it ideal for hiking and air travel as the combined weight of the tripod and head is only 4 lbs. However, if you lean against the legs (as I like to do to brace them) they will flex. It comes with a stone bag which solves this problem, but I'm just not going to hunt for stones every time I want to do a long exposure, so I drilled a hole in the bottom cap to take a large hook, and I hang my backpack from that, and that works well. So for your needs I'd probably suggest something heavier and with more side-on rigidity.
Good luck, David