[jon-wood]

Other than the points already raised around the client's contract with your employer possibly containing clauses saying they can't hire you away without discussing it with your employer I would be worried about any NDAs you've signed.

You're going to be entering an environment where you're still talking about the project you were working on day to day, but now you'll be doing so with a client. If you can make it an amicable move by ensuring both sides are involved in the discussion you're probably fine, but if your current employer doesn't want you going I could see them making use of NDAs to severely restrict what you're able to do, even if just by forcing you to make sure everything you discuss in the new job is meticulously documented in order to cover yourself in the case of future legal actions.

As others have also said, get a lawyer (your lawyer - anyone hired by either your current or future employer isn't your lawyer, they are the employer's lawyer) to review everything before making a leap.

[throwaway0905]

thanks, it did not occur to me that they might be able to make use of NDAs in this way (forcing me to document everything discussed in case of legal action), I guess this brings up a fundamental question on where the line is between company proprietary/protected knowledge, and then knowledge/expertise one builds up over many years working on and becoming an expert in a niche area?