I second what Hess says. It depends on the party you are with. We are usually only partied with guild members and it doesn't matter what level, what CS items, what class, what....ever. We play together because we enjoy it.
It all depends on who you play with, why you play with them, and how you play.
I am a cash shop user. The rest of my guildies do not hold it against me just because when I die I dont lose exp, thanks to my Blessing of Teva. They don't hold my cash shop enhance weapons against me. They dont hold my riders against me. And I dont hold it against them simply because they cannot use cash shop items. I would party with them even if they were a level 5. Haha, ask toolrocket,
.
It just depends on your outlook on the game. And the outlook of the people you are lucky enough or unlucky enough to meet in the game and on the forums.