The V-Rex is a great bike. I am converting mine to the new Rans HR-3way handlebar (use the B-72 riser if you want to try this) and will have it back on the road hopefully next Monday. I was just speaking to someone at Rans today about the square channel seat rail since I have some seat slippage. It can be removed - taking care not to let the rivets fall into the frame - and the new Rans V-Clamp can be used on the bare tube with their new seats. The V-Clamp has their new quick-release pin feature and is the successor to the Rad-loc. For now I will just use a bit of old inner tube to increase the clamp friction to keep the seat still.
You can also massage a Bacchetta Euromesh onto the V-Rex if you like that style. I have had fleeting thoughts of getting a Volae carbon fiber hardshell seat adapted to the bike but the handlebars are enough change for now and the stock Rans seat is quite comfortable.
Keep an eye on bentrideronline.com in the next few days for the upcoming review of the titanium version of the V-Rex, the Ti-Rex.