UO ortho Abbe or HD?

It seems the 9mm focal lenth is the sweet spot in magnification for the seeing in my locale. I cannot often go over that magnification. I have a Nagler 9mm T6 and an old Meade 9mm orthoscopic, but wish to exploit this magnification range more with eyepieces in this focal length. I plan on purchasing the Pentax 10mm XW from Herb (somebody's got to pay for all of this free speech), but I also plan on a 9mm ortho from UO. I have UO's 4,5,and 6mm so know that they are of a reasonable quality at a more than reasonable price. Who has directly compared the Abbe and the HD and is the HD worth the extra $20.00 of expenditure?

If your conditions don't normally allow for a focal length shorter than 9mm I'm not sure you're going to gain anything with either U.O. that the Meade ortho or Nagler offer you in the same focal length. The Nagler is a pretty nice eyepiece. I've heard the difference between the original U.O. and the HD is slim. For $20 I'd just buy the HD, it's not going to break the bank.

The HD has a flat top and I preferred the volcano top myself, coatings are marginally better.