I suppose technically the term Pay-to-Win is correct in regards to Planetside 2. But there's a compromise to this model which, imo, shouldn't be that big of a deal really. It's a AAA F2P title FFS. You can't expect them not to do this. They let people play for free! If you put money into the game you should definitely get perks like being able to have access to certain things before another person who doesn't pay. SOE is supposed to be going a step further and making different stats for the purchasable side-grade weapons. I'm not too keen on how the whole side-grade thing is going though cause as far as I can tell currently it's a bit more then a side-grade when you can purchase a weapon that gives a lock-on ability vs. the stock one. I didn't really look to see what stat difference they have, if they have any at all, but that could be that way because they simply have not gone through a balance of such thing.
A true pay-to-win model wouldn't allow non-paying players to obtain items without paying.
EDIT:
How do you define "pay to win" in a MMORPG?