So you locked down your sales team and the techies who drive the value of your intellectual property (IP) with a solid, enforcable non-compete executed at the time of hire. Sure they balk and complain, but you get most of those signed. Congrads, smart move.
You're either a sucker or rationalizing to avoid the conflict. Of course, your top HR talent and anyone who recruits should have to sign a fair non-compete.
Think about it - we're talking a narrowly drawn non-compete. Your top HR team members (I say manager and up) and anyone who recruits should have to sign one. We're not preventing them from working by signing the non-complete, we're simply agreeing that they won't take all the training, contacts and candidates that they've cultivated during their time with you to your most direct competitors.
A narrowly drawn non-complete doesn't mean HR pros can't find work. If fact, the HR game is one of the best in terms of its talent being able to cross industries and work. That "career portability" means your HR team can sign a non-complete that's properly drawn (example - we're a software company and you can't go to work for another software company in our city/industry or that recruits developers proficent in the same programming language as our company) and find work pretty easily if they're talented in the HR game.
Why wouldn't you ask them to sign a fair non-compete? Because you either don't think they're talented enough to get the same job with your top industry competitor, or you don't want the drama of walking them through it and requiring it.
Either scenario sounds dicey to me.
Draft the non-compete and put it in front of them. Explain the narrow parameters and require them to sign it. You'll be happy you did somewhere down the line.