i'm onboard with steephill, Shockers are the best spools in my opinion, DM's have an LPR which is nice, but just more stuff to go wrong, setup a shocker right and it will outshoot a DM all day long, plus, depending on the upgrades you decide to go with, you can do it in stages
Umm their almost all user serviceable? Who cares about color when chances are your going to put some kind of tank cover on it anyway? Besides the bottles are all made by the same 3 or 4 companies anyway, and have to meet the exact same federal criteria. The only difference truly is the reg, and for 95% of players the GAS tanks are perfect for what they need, and IMO ninja's aren't worth the extra money, just a bunch of hype.
I agree on the non-adjustable stock, couldn't care less about FSR capabilities or mag fed capability... honestly i'm surprised FSR's have caught on as well as they have since they're so damn expensive to shoot regularly.
As far as the price of the Dfender goes... well the things cased in MAGNESIUM... that shit aint cheap, and is a helluva lot more durable than aluminum. The strength to weight ratio is crazy, I mean Le Mans racers have been using magnesium wheels for ever because of weight savings. and in an application like this you will most likely NEVER see one that has a faded color or all nasty scratched up