I have to say that I've had a lot of bad luck with the USB-over CAT5 extenders.
After installing an XTB-IIR next to my breaker box, I wanted to move the CM15A there (to plug into the XTB-IIR). I already had two two VERY expensive ($250 retail) units from NTI, (I had gotten them free when a previous contract was cleaning out an old server room). Neither one of those worked properly for me. I would get random "resets", where the USB connection would drop, for just an instant, causing the CM15A to reset the connection to the PC.
If it happened while commands were running, the PC didn't hear them, or log them. Several times, there were a few resets in a row, which caused the connection to lock up, and I needed to reset the CM15A AND the PC.
I tried running the CAT5 a different route, running a new CAT5 cable, and even using powered hubs at one or both ends. I bought a $10 extender from Monoprice, and a $60 extender from Microcenter. All of them had problems keeping the connection up 24/7.
Nothing seemed to give me the stability I needed. I was playing with this over over two months, trying every combination I could think of. The longest I ever had it run without a reset was about 26 hours.
I even put in a new USB controller in the PC, thinking there was some issue with the PC. That didn't do it either. I tried another PC. Same problems. There was just something in my house that created enough interference to make the extenders fail with my CM15A.
I finally gave up, and used a long extension cord between the XTB-IIR's front outlet and the CM15A (I marked it as "X10 Only" every 10 feet or so, and at both ends). I was then able to use a standard length USB cable to connect to the PC, and my system has been stable ever since. It has been about 2 weeks since I did this.
As for the RF reception, I had done the non-invasive "18.5 inch reflector" mod (I taped an 18.5-inch length of wire - in this case 12 guage electrical wire, still insulated alongside the CM15A's external antenna) right after I put in the XTB-IIR, and that gave me excellent RF coverage in my entire house. I was reluctant to move the CM15A (which is why I spent so much time trying to get an extender to work), because I was afraid that I wouldn't get the same coverage at the other end of the house.
Boy, was I surprised! with only the "18.5 inch reflector" mod, I still have excellent RF coverage, all over my house. To be fair, the house isn't all that large (one story with a basement, about 1400 sq feet each), but it works great for me.
I recommend you try that first, as it only takes a few minutes, the materials are nearly free (most people already have extra wire, or even a wire coat-hanger, and some tape). It doesn't void the warranty at all, and I think everyone who has done it has gotten improved reception with it.
Let us know how it goes.