I just tried the HF 18 gauge nailer, not the very similar combination nailer/stabler. . . I did end up returning the nailer. One problem ... no depth control. . .I will probably be buying a Hitachi (~$56) or Porter Cable ($77).
You should check the fleamarkets, pawn-shops, CL.
The Porter Cable brad nailers bring $30-40 used. The 16 gauge bring $40-60. The $15 gauge angles go for $70-90. Framers, $80-120, BUT with a framer, make sure you know what you're buying (full head vs clipped head)
I've got one of each of those, and they're all happy with the HF nails, however, many of the PC nails are galvanized unlike the HF nails, so no rust bleed through issues with those.
At those prices, I couldn't justify buying the HF versions, but I did own the 6-in-1 older style blue framing nailer. I put a box of 3000 nails through it. It was pretty reliable, but only ran well when heavily oiled, and that included dripping a drop of oil straight onto the hammer each time I reloaded two strips of nails (skip that step, and it would jam).
BTW, believe it or not, the HF does in fact have depth control. It's that thumbwheel on the safety bar. It is supposed to work like the ones on the old PC nailers, but it's not accurate, and not very repeatable either. Maybe that's why it isn't mentioned in the booklets.
I would not buy a used pin nailer of any sort. They're too persnickety. Same thing goes for HF pin nails. When the nail has no head (and the hammer is a pin the same size as the nail), there's no room for error.
I don't know if the HF pin nailer is good or not, but I wouldn't buy it for one simple reason. It has no safety mechanism. At least the PC version has that cheezy plastic secondary trigger.
On that note, has anybody noticed the ridiculous trend of people trying to sell used HF stuff for more than you can get it at the store?
Seriously, if it's an HF tool, I'm buying it new. At least if/when it quickly fails, I can bring it right back.