I've got one and have used in on outdoor fields many times without problems, loaded up with. 28g bbs mine will happily keep up.
The only things to be wary of are,
1. The plastic body can be a bit fragile, especially round the pins at the back. This isn't a problem if you run it without the stock
2. If you get the one with ris rails battery changes are a pain in the arse. You need to take the whole rail off before you can even disconnect the battery which involves 7 small nuts and bolts which are easily lost if doing it in the field. I fitted a peq box as it also allows me to use a bigger battery (in both size and voltage)