Yes, Marines do wear LBVs... over their interceptor vests, all School of Infantry students are trained with that load-out... but in the field as a grunt you don't do anything without a "flak and kevlar" your not allowed to operate or ride any military vehicle even stateside without wearing these. The vest is a pretty essential part to the kit. So, by all means you can pick up an LBV for now (make sure its the correct issue... i don't remember ever looking at the specific designation... kinda negligent i suppose) and just make sure you pick up the repro Interceptor vest. OR just save up for the vest and look at cheap molle pouches at
www.cheaperthandirt.com. The LBV alone wont be that much cheaper i imagine and with the vest will probably cost you a lot more in the end. As far as the MOLLE pouches are concerned, standards are pretty loose and if you showed up with some OD on there you may get a raised eyebrow but thats about it... (and the older stocks of interceptor vests are old woodland but most newer ones issued are coyote brown, even for "greens" uniforms so its really kinda mix and match...) I hope this helps.