Top Law Schools

I just started at a firm in September, after clerking at a SSC for two years. When I accepted the job last fall, I asked to be considered a 2nd year (and get that salary) in recognition of my clerkship. They said no and the reasoning was that they didn't want to upset the hierarchy/go against their normal practice, etc. Instead they gave me a starting bonus that put me around a 2nd year salary, but that's it. I'm in a small state so not giving credit for clerking isn't that unusual. I thought I was ok with this (and their explanation) but now I'm there and getting really great reviews. There are only a handful of associates and I'm getting a lot of assignments over them even though I'm below them seniority-wise. I'm starting to feel like I sold myself short. They consider salary/bonuses during annual reviews in Oct/Nov. Another firm contacted me out of the blue asking if I'd be interested in a position there. They would consider me a third year. The firm is bigger, different city, same state, and is arguably more prestigious/well-regarded. I told them I likely wouldn't be ready to switch positions yet, but I'm going in for an exploratory interview next week. Would it be a bad call to leave my firm so soon? Would the class bump (and salary bump) be worth it? Is there a way to use this to have my firm reconsider my salary before next year?

TL;DR Leave decent firm after 3 months to be considered a 3rd year associate (and get paid more)?

Only you can answer this. Changing cities is a big deal, but all else equal, go for more money. If you're going to leave current firm after just a stint though, definitely make real sure the new firm is the job you want because current firm probably won't take you back.

I'm a bit confused by your take on your reputation at the current firm. What does "I'm getting a lot of assignments over them" mean? Is there some sort of work that is particularly desirable that you are getting and they aren't? If you are paid to be there, you should be getting assignments. I wouldn't take this to mean you're the next Alan Dershowitz.