I have to agree with the latter statement. While I have no experience with R3400, I have been using the
Primochill black in my build. It starts out nice, looks great, ain't 'sticky', ain't a dust magnet, and the min bend radius is good. However, over the course of a couple of months, the tubing has shown a number of signs of what I would term 'shape degradation'. Smaller radius bends - and not excessive, mind you - started out fine, but have now flattened a bit, although not to the point of kinking. Vertical 180-degree tubing runs connecting two CPU cooling blocks in the same cooling loop are noticeably 'sagging' a bit under their own weight. I use compression
fittings throughout, and at every connection the tubing end has become permanently enlarged noticeably. Since I have a fair degree of overkill in my cooling loops, my temps are not that high.
Granted, nothing is kinking or leaking or seriously wrong. Rather, after only a couple of months of service the tubing is sort of showing like a pair of 18-year-old tits 50 years later. When I'm up to replumbing the rig, I think I'll move to R3400.
rubidium