Its been a while, but progress is being made. Last night my lovely lady and myself installed the PEX tubing in the floor!
There is a short prequel though. I found that the joist cavity I drilled into for the tubing to go down into the basement is the one where my 16" wide field stone basement wall sits (parallel to the joists, so its enclosed). Thankfully there was an opening to run some plumbing, but it was not large enough. So, I had to chisel the the small opening I had farther open to get a tool up in it to grab the PEX tubing as it came down through the floor. This took a bit of time and delayed things nicely.
Anyway, the PEX tubing went in very nice the with the RHT heat spreaders. It snaps into the groove and it holds quite well. I only had a few issues on the hairpin turns where the tubing would pop up a little. I put something on top of it to hold the tubing down, and after it set a while it seemed to be happy and stay in position.
Here are the pictures:
