True, most DMs (in airsoft) use semi-automatic electric rifles such as a modified G3 or M16. You don't need a ghillie suit since you will be following your main sqaud or platoon.
The DM is supposed to deliver fast, accurate fire to an attacking group like an ambush.
But you may not want to do that since you already have a rifle, but what rifle do you have?
If you are serious about the DM role, then go out and buy some M16 variant and add a longer barrel, better gears, a scope, and maybe a bipod. Or just buy a TM PSG-1 and a scope and that always works.
If you are looking into getting another gun I would seriously consider a G36 or M14, because of the superior Hop-Up. It is true that stock TM M14's have the range of M4's or m16's that have been upgraded. I can't speak for G&G, CA or any of the clones. As for the G36 this is also true to an extent. G36's do not quite have the range of M14's but they are very close. if you are willing I would go with a G36 because of the weight ratio between a M14 and a g36, unless you are one who hits the weights ALOT.
The thing is I like spring guns more because there are less ways for them to break than an AEG (ex. battery wires accidentally getting cut, have to worry about battery life, and wind up mags are annoying while playing an intense game, etc.).
My next gun I will get (if my parents let me) after my current rifle dies (hopefully soon, which is a MP-001) will be a CA M24 and upgrading it to about 420 FPS.
Bob I agree with you around 100% besides your FPS. If your going to want to role DM and Sniper your going to want 500-550fps.
This gives you the range of a sniper and still the effectiveness of a DM.
I play the role of DM. I have a ghillie, a 500FPS rifle, ect. I like to think of the role more of as a scout. I go alone but I play with the team. Ill branch off on my own to see how far the enemy has pressed on but I will role with a group when necessary.
Bob, I usually run as a DM with a bolt-action and my MK23 as a sidearm. I simply wear a nice pistol belt, a holster for my MK23, and a canteen pouch for mags, radio, etc., and some knee pads. This is the best picture I have of my loadout if it helps. Although here I had my MP7 instead of my MK23 as the MK23's Mag was broken.