I'm not sure where you're getting your information, but it sounds like it's from Ultimate Guitar.
There are no drawbacks to changing your bridge pickup. However, you just started out, so I wouldn't worry about actually changing things up yet. Worry about playing first.
If you really want to do this, consult a tech in person. If you get a bridge humbucker, and you're not sure about the impedance of the single coil and neck, then a tech can help you find one that won't sound out-of-phase with the other pickups.
If you're changing one, I'll suggest changing them all. There are H-S-H sets, and if you stick to one brand, like Seymour Duncan, then you should be alright.
That's just my opinion based on my experiences, though. You'll find as you get better, and more interested in tone, that you'll want a guitar that comes with good hardware and pickups off the peg. Not all players, even advanced ones, agree with that sentiment, but I know that when I buy a guitar, I want it to be perfect as is.