I liked best the bar of Jyoder with the offset center made out of low-friction ring and I'm working on it (ordered the parts).
Have been using it multiple times a week for 1 year and no issues. I do think it might bind more with thicker depower rope as hole is round, not elliptical. I have PU tubing on my rope and when I crank the bar hard 90 degrees with big foil kite, it does bind a little bit, but so does any bar with a PU tube covered rope, right?
No issues with it binding due to rotating bar against offset hole.
How much pressure difference you expect? If you fly to space into complete vacuum /closed at sea level/ it will have 1 bar internal pressure. You really think that 25mm carbon tube with more than 1 mm wall crack at 1 bar?
Not tested yet, but I found a quick and simple solution to the problem of the middle hole. It requires a short piece of rope (nylon in this case) and a single round hole in the bar.
Sure, rope on rope is not ideal, but: it’s easy; very cheap middle loop (literally pennies) takes a minute to replace; maybe use a PU tube for the dyneema; find some other way to reduce friction.
Are you guys making the bar completely airtight or do you have a small hole somewhere? I am a bit scared my bar will crack if I bring it on a plane...
I would suggest it either needs to be completely airtight or completely open (to drain easily). Anything that is nearly airtight is likely to take on water and be difficult to drain. Eg hot bar on the beach, cools down in water, sucks in water.