All record sash cramps that I use, would second hand not be an option. I see from time to time second hand examples on market stalls if they are not too bent or you could refurb with wire brush etc.
I like the look of Bessey and for the last 8 years I have been using also quick clamps but I always seem to rely on the good old Record Sash cramps for shear clamping power, quick cramps do not get the shear pressure on do they. The Sash cramps bolt together easily to give extension to length and I do have a selection of both heavier made jaw/thread and the lighter model. I did use two clamps that were over 12 foot I used them on large door manufacture in my apprenticeship, I was working for an old family joinery firm they had all the wooden shaped planes in a cabinet/foot operated mitre guilotine and those clamps. All that gear was far older than me and was working fine and probally still working today who ever bought out the company. I was made use them wooden planes to do some moulds because I cut some machined beading short, my journeyman said it was a lesson, it was, I was there ages running it by hand. I never cut beads short again.
Only issue with sash is marking and glue deposits, some of the PVA I use eats metal if left alone. Had a lot of bother once with a finger jointer machine particular prone to rust/pitting so you had to barrier cream the metal bits of SET/Carousel/clamp and clean down after use.
I used to make ply covers for the jaws so you did away with blocks. Least they were always in position, the paper/shrink wrap I always seem to forget to have it handy and end up with blocks or the good old ply plates.
Allylearm