in my personal opinion i would get the map packs. i know it sucks not having some of the good guns but you do get more guns with the maps. so instead of picking from the 5 or 6 guns in each class you get to pick from 15-20 guns. you will have to complete a assignment for some of them but most of them are easy.
so i would defiantly go for map packs instead of the "shortcuts". why pay for something that you can have for free by just playing.
another note- double XP starts this Thursday and lasts for 96 hours. so you could unlock everything and still be able to play with us on better maps.