I had the exact same (post-installation "booting") issues/problems as the OP (@rjprice), of this thread did.
It has liitle to do with the (HDD)disk, and if it does, it's because of a "possible" faulty/buggy ZFS installation problem with PCBSD 9.1 (x64). ?
I did the same clean install again, but instead of selecting (the default) ZFS,
I opted for UFS2, and everything booted up fine afterwards, ...
And, just to double-check, I tried a few default (ZFS) installs, with/without GPT, and with/without Boot Loader ...
And in ALL the above scenario's, it (appeared) to install successfuly, but upon reboot, it hung ... ???
I did this, to eliminate the possibility of ZFS and the "PCBSD Boot Loader" having a conflict, and also to eliminate the possibility of it being my "disk", which is ridiculous, since this disk has installed/booted up with FreeBSD 9/8.2/..., as well as a couple Linux distro's(sry, but I had to mention this),
, with NO problems. !
If I use UFS2, (instead of the default ZFS installation), everything went fine, booting, in PCBSD 9.1(x64).
Hopefully, the PCBSD devs,..., are working to fix this possible issue in PCBSD 9.1(x64).
Edit: I've read around that "GAG" may be a possible solution, but I hope this is not a permanent one?.