Knifeedge software don't sell just the software - the controller has the copy protection hardware built into it, and really it's the controller you're buying. If you really want to use your own radio you can plug your controller into RF's and use the included one as an adapter. There were a few bugs when v4.5 was released but these were mainly fixed with an update that was released quickly.

The big difference from RF3.x to 4.0 was in things like flight physics, ground handling, the addition of water with flying boats and seaplanes etc which advanced in a quantum leap and put RF way ahead of the competitors in terms of usefulness as a training aid. The main changes from 4.0 to 4.5 were cosmetic... more/better sounds, shinier planes, better scenery and so on - all of which will bog down a less then optimum computer. All these cosmetic features can be disabled in the program's setup however so you can get back to 4.0 performance. I run RF4.5 on a computer that was within hailing distance of "high end" 3-4 years ago so it's pretty average by today's standards... AMD Athlon 64 3500+ (single core), 1.5GB ram, Radeon X1300 gfx. I have most of the settings on medium with clouds turned off and I get good performance out of that. I also occasionally run it on my laptop (Intel Core 2 Duo 3GHz, 2GB ram, Radeon Mobility X2300) and get similar performance, perhaps slightly faster. I'm not looking for pretty planes, I'm looking for realistic physics to keep my skills up when I can't fly.

The other advantage to getting RF4.5 is that the five expansion packs which used to be an extra cost have been made free downloads for this version, as well as all the user-created planes & airfields that are free. This is due them changing the the way the software's written between version 3.x and 4.x. All the peopel who'd bought the expansion packs would have complained if they hadn't been able to use them with v4.x.