Oh, need to check for comments more often!
Dan: No special thermocouple used, just a normal Type K straight off of Amazon. Cut, stripped and wired directly into the PID inputs. As far as I can tell the temp hasn't been abnormal. As for attaching it to the boiler: just a simple ziptie. Nothing special, but not necessarily the way I want it to be in the end. It's good for getting it up and running quickly, but in the end it needs a little thermal compound at the least and inserted into the boiler at the most. Again, the temp hasn't bee so far off that the PID hasn't been able to control properly. You'll also notice that there's no insulation, so I'm not exactly helping the osPID unit out any. That said, the osPID has had no trouble keeping the temperature within +-3degF.
Cracked: It's an E61 grouphead, but not a "true" E61. Just a generic. May have been off an Isomac, but who's to say. It was sold as used, and I had to clean it up, but it's worked just fine with minimal leaks, and I haven't even replaced any of the seals yet. As for the boiler, it's homebuilt. I had the idea kicking around in my head for quite some time, and when I found the grouphead, I started putting it together. The heading element is from a electric water heater and the HX is also custom built. Technically, the grouphead and the steam wand are the only two parts that I didn't build. It's been a fun project, and I'm still tinkering to get it to work the way I want it to. Many details that need to be fiddled with to get it to work just right.