For reference: My friend and I had a D5 running at low-restriction for about 2 years before it failed. It was really just the restriction of 10' of 1/2" tubing and a few inches against gravity.

That said... it still concerns me that it's higher stress on the motor. I'm also thinking/hoping that even CPU/GPU loops on a T3 (like loop #1 at 3.47 gpm) might be enough restriction to avoid problems.

If the T3 pans out then my next setup will either include that, or I'll go all out on an RD-30 with 5/8" - 3/4" tubing and puss out and run it at 15-16v for silence.