Besides not working very well in cold weather and the occasional magazine leak (If you dont look after the mag's). But if you get a higher mAh battery it will last a long time. Also I run a 9.6v 1500mAh and it last me over 1600 shots which is plenty. Also I know alot of people that play with just batteries and they have no troubles. Really its a choice of opinion GBBR's seem new in Canada (1 year).
Primary- SRC G36K
Secondary- KJW M1911A1