Just checked with Alexa clickstream and we get 27% of our inbound traffic from Hosting Discussion. I'd say that's significant.
I know when we had some banners on here we did pretty well too. We target a different market than what HD caters to. We mainly deal with end users, whereas HD has a lot of web hosts discussing things and are prime candidates for purchasing dedicated servers and reseller packages.
At least, that's how I see it anyway.
Targeted visitors are the way to go, for sure. HostLeet has been featured in the HD showcase for quite sometime now and we have no plans of stopping. A good share of our clients come from Hosting Discussion. So, yes, I would definately recommend advertising on HD forums.