Groove Tubes MD3

Question

I have a Groove Tubes MD3 tube mic and absolutely LOVE it! I run it through a Drawmer 1960 mic pre/comp. straight to ADAT and get incredible vocals.My question is: has anyone with this mic had the upgrade that Groove Tubes is offering? Did it make a vast improvement? What was upgraded? I'm kinda iffy about sending it through the mail. I guess I can insure the f**k out of it and just be stuck with my Neumann U87. Boo-hoo.Terry Zorp Sonic Storage Systems