I had two Velbon 630s. I still use one, the other is retired with a minor defect (probably servicable). I have been entirely satisfied with both. Now I'm using a Gitzo GT3541LS and my second Velbon Sherpa Pro 630. I agree with what Jeff says.
BTW, the problem my older Velbon developed was that there are some washers inside the tripod leg which stop the leg sections from gliding apart, one of those washer went into pieces. If the washers are available as spare parts it's an easy repair.
The Acratech head is quite nice. I prefer level type QR, so would I buy another Acratech I'd buy it without QR and add one of RRS QRs.
I had a Velbon 630 and used it for several years before upgrading to something bigger and selling it to a friend. I never had any problems with the flip locks, in fact I really miss them since the twist-locks are a PITA in comparison, much slower to use.
IMHO the Velbon 630 is a better tripod than the Gitzo 2-series or similarly-sized Fiesol.