I landed an agent from a small boutique agency in 2014 & she successfully sold my first book (it comes out in October). The advance was okay (nothing earth-shattering) and I'm thrilled about being published. However...when I see books like Jessie Burton's The Miniaturist or Emma Cline's The Girls getting huge advances, and realize that those authors have extremely successful agents, it makes me want to pitch my next novel to these so-called super agents.
Maybe this makes me a bad person and completely disloyal, but I'm quite ambitious (aren't we all?). I've read your past posts about switching agents and would be willing to start my agent search again (realizing there's a chance it might end up in abject failure). My question to you - is this unwise? Should I be counting my blessings and staying put? Or should I be doing everything I can to put myself in a position to succeed?
You're going to get some heat in the comment column for even asking this question, so best put on your asbestos underpants right now.
Whether any of those "superagents" is even going to want you is pretty much dependent on how this first book sells. If it sells off the shelf and gets a big ass movie deal, well, sure, you'll have some interest.
The chances of this happening are less than lightning striking and killing you. [There are 40-50 lightning deaths in a given year. There are a lot fewer breakout books.]
You say you realize "there's a chance it might end up in abject failure." The truth is there is an extreme likelihood this will end up in abject failure even if you have a good book, even if it sells ok. That's just reality. Those "superagents" get lots of queries. They get to be very very selective in who they take on.
So, the answer to this question simply depends on how much you want to risk. You can sever from an agent who got you book deal and query someone you think will do a better job for you. If you can't "land" a new agent, you're going to be a lot worse off than you were before.
Since you're quite ambitious (and I don't fault you for that at all) you'd do a LOT more for yourself by making sure this first book is a huge success and having agents try to swoop in and steal you away (this is called poaching, and it's reviled by everyone who doesn't practice it) rather than trying to query your way to the top.