You might want to try and determine the bottleneck before investing in a new or different array. If you're getting the data rates you listed, you should be able to capture uncompressed HD without issues.
So there has got to be an issue somewhere that's causing the data stream to hiccup during capture.
How is the current data array cabled to the Velocity?? Does it use the SAS connection as you noted before? I've not heard of that being used for video editing before, but I suppose it should work.
Chris Blair
Magnetic Image, Inc.
Evansville, IN
http://www.videomi.com