I guess that I'd ask yourself if it's really a need, or just a want. Sure, it would be nice to play on a kit better suited to the venue size, but could you get by with what you have? Probably. Right?
I get what you're going for. My husband owns a recording studio, and I seriously couldn't even tell you how many drum kits he has at this point, yet he's still lusting after 1960s Ludwigs. But he won't be getting them until we're well able to afford it (we don't have debt, have a year's worth of savings, and have almost paid off our house, but we're incredibly behind in retirement and investments).
He's had to make due with what he's had in terms of a lot of studio equipment for the past 11 years, but he's still booked far in advance. So it hasn't hurt his career much, if at all.
I'm probably the wrong (crabby) person to ask, but I think that you can wait and through your entire tax refund at the student loan. Less fun, but probably more responsible.
(But if you do buy, buy used. Surely you've got friends/acquaintances who know someone selling drums. If not, Craigslist.)