I've had my (G&P-internal parts/upper & lower receiver) WA M4 for some time now and have used it in 2x12 hr night games with cool-ish temps and a few (hot) day games having experienced no real issues other than power drop-off as the mags cooled along with the odd double-feed. Keeping to single or double-tap shots however resolves the cooling effect and double-feeds certainly make the overall experience all that more realistic. Reliable mags for the WA are still a thorny issue (slow leaks) unless you immediately take them apart and install the G&P o-ring kits but otherwise, I've been using propane exclusively and can honestly say that I prefer GBBRs to AEGs. Winter ops are another story but I don't usually shoot outdoors in the winter anyhow so it's a non-issue for me. As for velocity, combine a PDI 6.01 inner barrel with the NPAS system and it's pretty much as good as you can get with a WA-type GBBR. I also very much like the concept of realistically-limited rds per magazine which forces you to play "smart" instead of imitating a fire hose.
Brian, if you think the WE AWSS M4 field strips accurately, you should see the WA version. Both the BCG and trigger group are extremely realistic when you compare them against their real-world counterparts. As for realistic weight...I dunno but I'd say both the WE and WA are very close to the real thing. I do know however from first-hand experience; you probably noticed me huffing-n-puffing my way up and down those FR hills during the Terminator game last month, that a full load-out with these guns & mags
is heavy and thus a very good work out indeed -- I was thorougly exhausted by morning!
I whole-heartedly agree with you that a properly set-up and maintained GBBR is
THE best toy to find its way into a tickle trunk in a long long time.
'Fly