Thanks! Will check out the Fathead II and dig up your MXL reviews.
The Fathead and Fathead II are the same mic... the II just has a nicer shockmount.
I have a Fathead w/ standard transformer and an R40. Both mics are great on guitar cabs. For acoustic instruments they're both very woody and warm, but can be way too dark for some instruments. I love using them on viola da gamba or upright bass. For acoustic guitar they work great for more of an old school subdued sound, definitely different from the modern small diaphragm condenser snap typically heard today.
Of the two mics I like the Fathead better but they're quite similar. Keep in mind you need a LOT of gain to use most cheap ribbons on the market. Here's a little test I did with the Fathead, not a lot of EQing going on. Excuse the playing