Well, I just took the plunge and got the TST 507RV. I called TST and they matched the lowest price that I could find on-line, and threw in free shipping, a three year warranty, and free programming. I decided against the flow through system as the batteries aren't user replaceable.
The system came in the mail on the third day after ordering.. now that's fast! Everything was already programmed, and all of the transmitters were pre-labeled for me. Great service!
Now, here is where I need some help...
The only two transmitters that I could get on (because of not enough room) were the two on the outside rear tires. Those two worked great, and immediately returned the same pressure as my gauge showed.
The Redhawk came with the braided stainless steel valve extenders in the rear, but, darn it, there just doesn't seem to be enough room for the transmitters.