The flatline is very reliable,ive still got a 3000 flatline on a RT for 3yrs now & ive not had to replace a part or had any problems with it yet,other people that have own 1 have said the same when ived asked them also planet havnt had 1 come back for repair when i asked um.
All ive dont is stripped it every now & then(which is easy) also reoiling it.It can cope easily with a RT on full reactive so u'll have no problems for a E-mag wot so ever with the flow rate.
Ive upgraded to the 4500flatline,no problems so far.
Ive had the odd problem with the max flow,generally a ok reg.
Air is ok & reliable but ive been told it can be a pain (very reliable source),coz it keeps swithing it self off every 30 secs or so if its not havin to do owt to save the battery & when it does switch itself off u have to keep telling it wot settins u want it at- ie wot pressure or wot gun its for etc which is a pain if it does it during a game! or so ive been told!