I have also tweaked a customers Fostex drivers with Dammar and it sounds great.
I believe those were my drivers....
I'm mighty impressed with the difference a few coats of (admittedly high quality) varnish can make to that fostex driver. I tried out the FX120 while I was waiting (why before anyone wastes their time doesn't work in such a shallow enclosure), but I'm really happy with the sound you managed to coax out of this part. I'm looking forward to the hemp driver and am curious how it will compare to what I'm listening to now, but either way I think this coating takes the FE127e to a new level, and it might appeal to those looking for a possibly slightly 'faster' sound than the hemp cone, but keeping an even tonal balance.
What's interesting about the hemp design is that it was designed after the cabinet - from all the revisions, it's clear that the specs of the driver have been tuned and retuned with a specific cabinet in mind, so I'm interested to see what that translates to sonically.
My Sig. 30 arrived at the beginning of the week, and the drivers arrived back today so my little system is finally complete! I really like the simple clip system to wire in the driver - it makes swapping them out a 5 minute job.