I have an old ED80. Haven't bothered getting a better 80mm refractor because it takes a significant cost to do that and see a significant gain in overall image quality from many aspects. Works great with a Quark. Works great for anything that doesn't need monster aperture (planetary...). Visual and imaging. The stock focuser is ok. It can work for all of it. But a cheap after market focuser makes a big impact.
The stock 2" focuser is ok enough to use fairly heavy imaging trains. It's going to have some play in it. An inexpensive GSO focuser will change it significantly for the better. And a better focuser is even better of course, though expensive. The ED80 is a great piece of glass for its cost. The correction is fantastic at F7.5. A good focuser, even a cheap one, is a big upgrade for overall use.
Here's an ED80 with a simple GSO focuser slapped on it.
Check out the imaging train on that thing.
Handles a Quark just fine.
Here it is with a 0.8x reducer and an APS-C camera:
Some images from this system (forgive the diffraction spikes, I added those in post):
And here's the ED80 with double stack SM60 etalons (60mm F10) on front and a binoviewer and some imaging done with it in this setup: