[Schwag]

My 2 cents.

I have yet to see a stock gun that can run an 11.1v lipo reliably for long. 2 of the supposedly lipo-ready KWA m4s blew their boxes in no time at our field. Not even a summer's worth.
If you want to run lipo, you need a tough box perfectly assembled.
It puts a lot of strain on gears, pistons and cylinder heads.

Before putting both my guns on 11.1 lipo I added sorbo pads, double o-ring cyl heads, sorbo piston heads, sector gear clips(otherwise you probably wont be able to load bbs)
Titanium tooth pistons, metal bearing spring guides, solid metal bushings, stronger anti-reverse spring and a perfect shim job.
A box moving that fast also has alot of vibration within the shell. Proper body/shell fit will increase the life of your box.
V3 is stronger than V2 and better suited to lipo.

With this setup I have run my guns for over a year with only 1 issue. That is arcing.

On my mp5k, the lipo causes arcing between the trigger contact and blades. This scorches them and builds up a residue that will eventually stop it from working. Need to strip it and clean the contacts every few months. This has only happened on one gun. My other has no arcing. Don't know why.
This can be fixed with a mosfet.

Also remember that regular mini connectors(tamiyas) limit the amount of juice so your 11.1 won't be super efficient until you upgrade wiring and go to deans connectors.

The short answer is that if you can't build a gun(or aren't friends with a very generous gun doc) you probably should avoid lipo and stick to 9.6v regular batteries.

If you build a gun to handle it, it is awesome. Instant trigger response, great rof, I have never run our of juice and the cold doesn't seem to affect them as badly.

I have been using king arms stick and small pack in a peq. Can't recommend them enough. King arms rocks.