When I hady consulting group we did this only a handful of times. In almost every case we had the approval of the client. For those cases where we didn't it was

When I hady consulting group we did this only a handful of times. In almost every case we had the approval of the client. For those cases where we didn't it was a risk/reward ratio and the fact we felt the client missed seeing bigger picture we saw. Only had one client get pissy over it and they threatened and sent a nasty letter but once they talked to an attorney who told them there was no non-compete and nothing they could do except try and prove we used the service code (we didn't of course) it went away. Just because someone is richer doesn't mean they want to waste $100k+ chasing a maybe win. Also in at least a couple of cases clients came to us to buy our version. It is business and they weren't in the software business but into selling shit. So all they cared about was better tools to make them more profitable. And if we learned some stuff solving a problem for them that led to a better product later they were happy. I think this was somewhat unique to e-commerce though as I doubt a SaaS client would've felt that way. So make sure you consider that. Make sure your contract has you in the clear and then go for it. Get a lawyers ok if you feel you should just remember they are in the no risk game generally and Entrepreneurship is all about calculated risk, so not many lawyers strong suit. I have ignored lawyers advice as much as followed it, just having it though gave me the risk profile I needed so it was worth the conversation.