We don't want to list our developers with our agency on CH because they're going to get poached
First off, we can understand the concern. It takes a lot of work to find a great developer and get them onboard, and it's painful to lose one.
We would be lying if we said that there is no possibility that a developer of yours could be contacted about an opportunity that they're interested in on CH. That said, couple of important points here.
#1 - It's already happening. They're being contacted nonstop on LinkedIn every day of the week. You can't stop the free market. What you can do is create a compelling work environment that makes them want to stay. If your developers have been with you for a while there's a good chance you're already doing that. In which case, kudos to you.
#2 - Ultimately you have to want what's best for them - if an employee has an offer that's more in line with their interests and pays better, you'd be doing them a disservice by not encouraging them to take the job.
#3 - We're not going to use slimeball recruiter tactics - we're not going to call the office pretending to be asking a technical question only to try and poach someone. We're building a service that hopefully has value to developers outside of hiring and our goal is for them to gravitate to it for that reason. We will also have preferences that allow developers to decide how and whether they want to be contacted about job opportunities.
We know that recruiters can sometimes tend to paint a rosy grass-is-greener picture for developers and create a lot of churn in the industry without creating lasting fulfillment for developers or employers. That's one of the reason that people hate recruiters.
We don't want to be a business that people hate, and because we're fairly active in the community, we'll hear about it if that's what we are creating.
So you know, this is basically the business model that Stack Exchange has - a company that virtually everyone has a lot of respect for. A service that your developers are no doubt already using regularly and have accounts created with, and are probably receiving notifications about job listings through.