Interesting inputs from all involved. The physics (geometric optics) demands the coma be the same for optics of the same f ratio. And the paracorr doesn't know how big the mirror is or its focal length, it just deals with the convergence angle of the incoming focused light. So while Bratislav's arguments are thought provoking (not a bad idea) I couldn't see how they would apply. I'll re-read them as the arguments are subtle.
The moral of the story (based on people's reported experience and the various arguments here) seems to be that for any Newtonian of f/8 or less, and especially f/4-f/5, with first class eyepieces, a paracorr is a damn good gadget to have available.
Thanks to all for the enlightening discussion.
One question arises: since astigmatism seems to swamp coma for eyepieces below a certin quality, at what point on the quality curve does a paracorr start to make a visible difference? Anything better than el-cheapo Chinese eyepieces? Something like the Meade 5000 series? Or only for things like Naglers and top Pentaxes? Comments aprpeciated.
2. Floaters: Don, if you find a way to deal with them, please post here!! My eyes are a zoo
DN