yes, as long as its accessable for the inspection

I have a unit in a high rise condominium which has banned the use of plastic tubing to a compression fitting from a fixture to the fixture stop value. I imagine it is because of incidents like I have experienced with a 3 story house (described below). Particularly insidious is the tendency to develop a very small leak which isn't detected in the room where the fixture is located because it is too small and leaks into the wall cavity causing damages far removed from the source of the leak which make it hard to locate the source. I am in the processing of cleaning up the mess from a long continuing and until recently not discovered leak from one of these connections from a sink fixture (hot water side) on the 3rd floor of a 3 story house with basement. Apparently for years, there was a slow drop, too slow and limited to be noticed as the water just seeped into the wall behind the fixture. On the first floor there was a bulge in the wall (interior) below the indoor unit of a mini-split system install near the ceiling, so some evidence of water where it shouldn't be, but, I suspect the lines from the mini-system and it didn't seem worth tearing open the wall to investigate. Over time (years) the leak seems to have increased and I found water accumulated in the basement floor (concrete) near where the boilers, hot water heater and water softener were located. I suspected first the hot water heater (so shut if off at the water inlet), then the water softener discharge as the floor drain had blocked. The water heater was turned back on. Possibly the surge of water in the lines (as often happens when water has been off for a long time) may have cause a water hammer effect which increased the leakage. In the end, I with a second floor ceiling collapsed exposing the underside of the third floor, I could see that it was a plumbing leak. It still took some time to find the bathroom (there were two above the ceiling with the problem because there was never a trace of water on the bathroom floor. All the water had leaked into the back of the cabinet at the seam between the cabinet bottom shelf and the cabinet back wall and from there into the wall. That was the most troublesome thing about the leak. It just wasn't noticeable until the ceiling collapsed. The most obvious suspect, the mini-split system located just above where the damage was initially evident had nothing at all to do with the leak.

Thanks for the response. Yes, the PB side has more barbs than the PEX side. I found info about the fitting on the net, and I provided a link to it (I hope it works). Take a look and tell me what you think. I know what your talking about with the PB cinch rings, but this fitting includes a ring for the PB side that is exactly like a PEX crimp ring. I'm assuming I can use the PEX tool, but I thought I'd run it by the informative people here first. Here is a link that might be useful: fitting details

So, is my understanding correct? No copper ring, just the pressure of the expanded PEX put upon the fitting? If this is the case, any tips for not installing it improper? (for a DIYer) I would be worried that I over-expand the PEX and then it doesn't seal right. That was the one thing I liked about the copper ring. Crimp the tool completely and you're done. (No room for human error). Just form the little I read must Plumbers use ProPEX. If it is the best, then that's what I want to use.