Yes in my opinion there virtually isn't any other type of battery I'd use in an AEG anymore:) And that's from someone who has been involved in the sport/hobby since the early 2000's. I started with NiCAD and later NiMH and then went lipo a few years ago. I'll never go back to using anything but lipo or some new battery chemistry.
Reason is both the ability to push power, but also they just hold so much more capacity wise and seem to be even less work to keep running well. Also within reason you can run most stock guns on a 2S 7.4v lipo without adding a lipo, and I haven't really seen too much of a detriment to trigger contacts and such over a NiCAD or NiMH battery in those cases. I've seen a few that failed, but I saw trigger contacts fail under the older batteries also. Now that said if you go to a 3S or 11.1V lipo then I'd recommend a mosfet, again you can skirt it for a while but that's a shorter run until the contacts fail.
Also a mosfet isn't a bad investment anyways for most guns doesn't need to be fancy(if you search I did a thread on cheap DIY mosfets), but overall I'd seriously go to a lipo and recommend it for guys. But you do need to research and learn the in's and out's of charging safely etc, but it's worth the learning curve.
Luke