What's your long term goal? Whether it's the "right" move basically depends on where you want to go.

Big -> small is usually people who went in, want to stay in public but want to slow down. i.e. they are thinking about having a family, want a smaller firm (big fish/small pond thing) or just didn't like b4.

I don't think you'll find the transition hard, and 40 people is still a relatively ok size. Some things to think about are: -What is the "culture" of the firm? Less people = less people to get along with. If you don't click with a few people, especially senior management, at a smaller firm its a bigger deal. -Will you advance at a rate you'll be happy with? It's relatively harder at a smaller firm to get promoted. You're competing against pre-existing staff, further you said it's a "flat" structure. How long until people usually get promoted? -Are you going to be happy with the work? Smaller firms have less clients and are likely to focus on certain areas, and have less variety overall. -Overall learning: Smaller firms don't have the training or development of larger firms, especially if it's not part of a larger network.