I have a FPII with a Stratos and it works very well. On first go I had very little hum. When I upgraded the volume control I also added more hum than I care for and thus it has been out of the system for awhile.
I think hum is very system and construction dependant. Some times you get it sometimes you don't.
sts9fan, there are a few cheaper simple tube preamps by ASL, nOrh, etc. available. If you can solder Foreplays are very fun and easy to build.
Lee, how would you compare the II vs. the III?