I own both Famas and G36C.
I would recommend Classic Army G36C as your first gun.You can put almost any
accessories on it. It has a reinforced Ver.3 gearbox, Upgrade is very easy.
I like the look of Famas a lot,so i bought one.
It has a Ver.1 (the oldest design from TM) gearbox ,and it is very difficult to upgrade or repair it.
I like the super high ROF(around 1100rpm with 8.4v 2400mAh Nicd battery)of this gun.that's pretty much about it.
If you really like the look of Famas,go for it.
It is actually not a bad weapon in stock form for CQB.High ROF does help a little bit in close combat.
I wouldn't mount a M203 becasue the handgurad is too weak to take that weight.You can drill holes and put a bottom rail to mount flash light or grip,but a M203 is just too much weight for it.
Here are some pics of my famas G2.(it is build from a famas F1 and a famas SV)
That's pretty much all the accessories you can get without modification .
http://www.airsoftcanada.com/gallery...6_original.jpg
http://www.airsoftcanada.com/gallery...3_original.jpg
http://www.airsoftcanada.com/gallery...8_original.jpg
http://www.airsoftcanada.com/gallery...2_original.jpg
http://www.airsoftcanada.com/gallery...7_original.jpg