I've been running a Perseus preamp for a little more than a year now. It's certainly the best pre I've owned and I have no desire to part with it.
I have no idea how it compares to the Athena or Hera II, but I find the sound it gives me to be fantastic. I don't find the sound "tubey" at all. What the preamp does give me is a nice wide sound stage, 3 dimensional sound, great separation, and great clarity. It is very quiet as well.
I'm sure there is better out there, but I seem to have a great synergy with my setup and it has never crossed my mind to "upgrade" it.