First off, let me state that I bought the xim for 2 main reasons:
First, I began my gaming days as a PC gamer. especially online gaming, as console online gaming could not be achieved until the release of the original PSN on playstation 2 and xbox connect for the original xbox. I did not get into online console gaming until 2 years after Halo 2 was released. Plain and simple: I am a KB/M player both at heart and by preference. In recent years, mainly due to Halo 2 and the fact that many of my personal friends are console gamers, I have been forced to play console games, and in fact, have grown quite used to the controlls even though I would much rather use a keyboard and mouse.
Seccond, I knew immidately that as soon as I got used to using a KB/M setup in games I was accustomed to using a controller in, I would become a much better player. This was true, after about 2 weeks I noticed an increase in my preformance, especially in gametypes like SWAT and snipers. I can use the pistol in reach as well as most players can use the DMR in mid range situations.
The Xim will give only some players an advantage, i.e. those who are good with both a pad and KB/M, and know the mechanics of the games they are playing. I have a friend on my friends list, also a personal friend (WhyIAmFamous) who will tear any XIM 3 user apart with a simple controller. He is a stand in for professional teams in game battles. a XIM would take him years to get better-than-controller with.
I have now introduced my girlfriend to gaming using the XIM3. Seriously. KB/M is way more simple for someone who has never played games before to learn. You try teaching a girl how to use a gamepad with 2 analogs. It is not easy. Same thing with your parents. She now quite enjoys halo, gears, dead space, and COD, although mainly the story modes, when only a few months ago she hated games.
The Xim3 can also be used with the G13. It occured to me that since the G13 has a much-more-than-eight vector analog stick in addition to 25 keys, the g13 could be used to allow people like our soldiers with one arm missing to play games once again. Thanks to the XIM3 they can now play many xbox games again (I guess only assuming that their right arm is missing, unless a right handed G13 exists)