I think that the shocks that they sell are OEM quality, so adequate to the basic task of providing suspension, but nothing near the quality you would get from Ikon, Racetech, or Hagon.
Personally when I finally replace my shocks over the Winter I plan to spend the extra couple hundred on Ikons or Hagons. I am going to hold on to this bike for a while and so it is worth the money. If you think you will be selling soon, then an OEM look set from David Silver would probably be fine.
Are your Showas rebuildable?