Though mine [the AimTraks] will be going on ebay when I get around to it!
Why?
Given you've already got the AimTraks, don't they work sufficiently for your needs?
Or do you simply have no interest in playing lightgun games any more? If so, why your interest in the Sinden?
I could be wrong, but I can only guess that you don't understand the difference. The word "true" is the key part of the Sinden statement. The implication is that it gives the same pinpoint, line of sight accuracy that old-fashioned light guns had with CRT televisions, which was never achievable with LCD screens before now.
Wii remotes were never intended to have exact accuracy. (Notice every Wii game that has "aiming" involved uses on-screen crosshairs.) AimTraks (and I have 2 myself) are basically a fancy Wii remote. Yes, these WORK with LCD screens, but you have to calibrate them and stand in EXACTLY the same place every time you play if you want line-of-sight accuracy (and who ever stands in EXACTLY the same place every time they play), or you're constantly recalibrating. Either that, or you use on-screen crosshairs, which I think is what most people (me included) do with AimTraks.
The Sindens provide "true" line-of-sight withOUT the need for on-screen crosshairs, and WITH the ability to stand anywhere without the need to constantly recalibrate. (I think there is a calibration, but you do it once for any given screen and then never need to calibrate it again on that screen.)
I was waiting to see the feedback on the Sindens from the production models before I jumped on board, but from everything I see/read/hear about them, I'll be buying a pair before too long and probably also try to sell my AimTracks.
That said, I also just discovered GUN4IR, which is a DIY lightgun setup using instructions that someone created and custom software for an Arduino board they wrote that also gives very accurate line-of-sight. So I'm considering that too.