So...I just added an F-2B to my rig.
Sadly, my S-F2 has stopped working, so I havn't been able to try them out together. Bass Central told me to ship the unit to Alembic for repair.
I'm very pleased with the warmth of the F-2B with the Skylark. The range of the thing is surprising, as is the volume it puts out. We've been recording in a large warehouse, and I wasn't able to turn the thing up pass 1. The low end is very very nice (though I also have to leave it set at 1, or else its too much). The high end can easily become shrill, so that is staying rolled back as well.
I'll be excited to try it in conjunction with the S-F2 once it gets repaired.