Yes, I do agree that the price of the XFPS IS pretty expensive. But I believe that many are missing the main point of the product, and underestimating its target audience. Please bear with me while I explain.
I remember playing Goldeneye 007, and Perfect Dark on the N64 and becoming fairly good at it. Shortly after obtaining my first PC, and with the persuasion of some of my PC savvy friends, I quickly became an avid PC FPS player; playing games such as Counterstrike, Desert Combat, and Battlefield 2. When I first started playing, I said to myself: "I must have an analog gamepad to play this". So in the short while it took me to obtain a quality gamepad for the pc, I played using the oh so awkward mouse and keyboard. The gamepad finally arrived, and I configured it to play very similarly to how it did in Perfect Dark. Even though I was still getting my a$$ handed to me as a noob with mouse and keyboard, I'll be damned if I didn't realize right away that the gamepad didn't feel as natural as the M&K with only a few weeks of playtime. The M&K just gave me more of a "I'm really holding this gun" type of feeling. After a while of playing PC FPS games the mouse literally became as an extension of my virtual arms which were wielding the guns.The day that I learned that the smartjoy frag was on the market for the same Xbox console which I occasionally played Halo on when someone would bring it into the fire station, was the exact same day I went out and bought a used Xbox of my own, and ordered the SJF. I didn't even think about any of the possible issues that the SJF may have had. All I knew is that having anything like a M&K would be much better for me than the gamepad for any FPS'. The guys at the fire dept. constantly heard "If I only had a M&K". Well, the SJF arrived, and it was exactly like I described: "LIKE a mouse and keyboard" it definitely didn't have the precision of a native PC mouse, because you could easily feel that the sjf would only allow the mouse to emulate the analog control of the left aiming stick. I'm not going to go into detail about how this isn't the same as aiming on a PC because this post is already long enough, but trust me, it isn't the same. But after much tweaking, I made it feel as closely the the PC as I believed that I could, and after just the first night of adjusting I went back to the station with my new controller setup, and have not been dethroned in Halo 2 by a fireman from any shift yet. And now, if I'm not playing Halo 2 with the SJF, I'm not playing it much at all.
Most people who are used to playing FPS' on PC feel the same as I do(trust me there are more of us that you think.) And although the XFPS may be costly, may not have good or any headset compatibility, and may possibly have other problems as well, people like me will not give one iota of care if it is combatible with Xbox 1, PS2, racing wheel, or WHATEVER. We can connect our freakin' mouse and keyboard man!!!!! And most of us will at least consider giving a portion our left nut for it. You want proof? Well consider this: There are two XFPS being sold on ebay with a "buy it now" price of $199. Watch as someone gladly pays for it to either give or recieve it before Christmas.
I know your eyes are probably bleeding by now, but I wanted to just say this: I've played with people on and offline that were as good, and better than I while they were playing with the controller.(Practice playing Halo 2 for awhile on sensitivities of 8 and 9, and also practice jumping and shooting accurately.) So don't feel inferior to someone simply because they're using a mouse and keyboard which is merely emulating the gamepad. That type of setup is just more familiar to us PC FPS freaks.