FWIW, many will say the EMS Topgun sucks and I am not here to argue that. I bought one when I first built my cab because I got it really cheap and I wasn't sure if I really wanted a light gun.
Anyway, once I got the drivers figured out (Win7 64bit driver signing issues), it has been working great for me. I like it for what it is, and I am able to play many of the light gun games with it without trouble. The aimtraks are better by what I have been told, but the EMS will work with a little patience and reading.
Been using mine for over a year now and I have no plans on replacing it right now. If it ain't broke, don't fix it.