Help me with this gun decision plz...

So... I used up some of the last ZP I had left from offers on crates and got an M4A1 Advanced for a week... tried it and loved it... usually I pack and AK and TAR21 into my bags but the M4A1 Advanced really really grew on me... so I was thinking if it would be worth buying a regular M4A1... I have about 130k GP right now and I was gonna buy RPK and DSR-1 when I get to that level (in less than a week I'm assuming) so that will pretty much waste all my GP... however... do you guys think I should get the regular M4A1 before and wait up on one of those guns? Or do you think at this point buying regular M4A1 is not worth it? I have lots of good guns already but no M4... here's what I have so far:
AK Silver
TAR
QBZ
XM8
G36K
(and other guns but these are the main ones and of course I have the AWM)

so do you think the M4A1 regular will be a good investment even though I already have all these guns? Is there a huge performance difference between M4 reg and M4 adv? (besides the silencer?) or should I just save up for a Skill Light just in case? (even though I really hate it I feel like I should have it as a joke eventually) any views on this whole thing? thanks guys!