I've done technical books for O'Reilly and John Wiley. As long as you are motivated and can finish on your own, I'd strongly advise self publishing. The money will be far, far better and you'll actually have control over the process. With a classical publisher, you will rarely get more than the initial advance. And, disturbingly, when I published with O'Reilly, I don't think I ever got statements showing sales. If the material you're writing is niche then I'd strongly advice LeanPub (I buy a lot of books there).