[MBAtarga]

Regarding the pipe clamp vs. Bessey K body (parallel jaw bar clamps like your picture above) -
the flat Bessey style clamps are fantastic - and would definitely be preferred over the pipe clamp style that have been in use for possibly 100 years. However, pipe clamp capacity is ONLY limited by the length of the pipe. If you've got a clamping situation where you need to clamp something that is 8.5' long/wide - pipe clamps are going to be the ticket. And it's very easy to take 2 6' pipe clamps - and put a $2 coupling between the pipes to make a 12' clamp. There might be ways to work around the bar clamp limitation - but pipe clamps are quick in that scenario.

Edit: As for bar clamps I've probably got about four 5', six 3' and a couple others, but I've also got three 8' pipes and about five or six other shorter length pipe clamps.