I have a 9T6 and 5T6 on a 20" f/4 Dob. They work excellently for me (no glasses) in DS observing, although I do not tend to compare a lot.
If you like see
http://eyes4skies.de/Internet/Astro/BeobachtungsReports/BeobachtungsReports_files/BeobReport_2008_05_08_KABR_engl.htm
If you can afford Ethos EPs, why not, but the standard Naglers also have become a bit cheaper now, as Ethoses are emerging... Maybe that's the time to buy the Naglers... :-)

Good luck,
Peter