Well, first, that's a pretty big step between the two.
If I were you, I'd get the M4 but pretend like you bought the SAW. Spend the rest of the money on GOOD gear. Get a radio, get good mags, get some nice gear. Having a SAW as your only (and I'm guessing first) gun would be suck.
The 249 has a PGC style gearbox, which is really ideal for high cycle operation. The V2 gearbox is real weak, mechanically, when it comes to that kind of stuff. Also, the 249 has a lot more going on, comes with a box mag, so on and so forth.
Buy a Classic Army M15A4 CQB. $415
Buy 8 (maybe 9) Tokyo Marui 68rd Standard Magazines. 8 @ $22 = $176
Buy two Gonzo crane stock batteries. $90
Buy 1 ICOM F4S from
www.reddogradios.com (call him and say you're from Arizona) with an extra battery, a Pryme handmic/headset. $150 (I believe) + 30
Buy a Weesatch/Wasatch or spend a little more and get something nicer. $120 on up
Buy a hydration setup. $50
You could do all that for about what a CA SAW costs delivered.
If by some miracle there's something left over from your budget -- buy some nice M-Frames.
That's like $1,030, which is like what a SAW would be once you got it ready to play. You could do some stuff cheaper, less mags, or King Arms (fine, I have some), maybe an Infinity Tactical chest rig from Jungletoy...those seem OK.
PM me if you need anymore help.