G'Day Baz,
Just for reference, check out any of my solar stuff for the last year or so, and you'll see what your ED80 could achieve with a Coronado SM40 on the front and a Lunt B1200 blocking filter. I'm not aware that there;s any visible difference in the quality of images from either the Lunt or Coronado stuff. They're both pretty good gear.
If you are a setup and tear down astronomer, or you are going to specialise in solar work, a solar scope is the way to go. I am still following the filter route as this allows me to use my ED80 in the obs without changing OTAs and rebalancing the mount (hence I preserve all my EQMOD sync points
). i.e. better pointing, and less hassle.
I am in the process of buying a Lunt LF60 full aperture filter to replace the SM40 even though the filter is more expensive than the scope!
Another reason why the solar scope are cheaper is they only need basic optics. With narrowband Ha you don't need to worry about chromatic aberations, etc.
I will say I am very happy with how my ED80 performs with my Ha filter. It has very flat and uniform illumination and no evidence of a sweet or hot spot.
My only limitation with the SM40 filter is due to aperture I feel. I struggle to get sharp images when I throw a 2.5x powermate in the train because I'm exceeding the resolution of the filter (hence the step up to 60mm).
Al.