Its very hard to find people playing in any DLC server (US servers mainly), thats why I regret buying both DLC packs. Besides, the servers hardly vary the game modes. The majority only have TIA and crash site game modes. Plus, the custom maps only run on unranked servers which don't register de achievements and stats.
If I pick one, I want the one that has the new gun. Which one is that? Decimation, the 2nd one, i got it earlier, the new maps are nice for a change and the weapons are both cool(the FY comes with all attachments included).
No do not buy the dlc's they are not worth it, because hardly any of the servers ever fill up. Its about time to give up on this game altogether, patch 1.9 is really broken especially for ati card users it really is a huge mess.