[gregbradley]

I see you have a QHY8 -good move.

A nice refractor with shorter focal length is always the better choice by far for imaging. Long focal length compound scopes require high end mounts to handle them otherwise you get eggs for stars and rotten images. hehe

The EON120 looks like its from the Taiwanese Manufacturer who makes William Optics scopes, Astrotech scopes. Very nice and a nice focuser/microfocuser. I use an Astrotech 66Ed scope for autoguiding and it is extremely well made and very affordable.

900mm is quite a good focal length for many objects. It is still semi widefield. You can download CCD calculator by Ron Wodaski for free and you can set it for various scope/camera combos and see exactly what size image it will produce. Very handy.
Google CCD calculator.

For 3Gs you'd be able to get a Stellarvue 90mm fluorite triplet which would be my choice. Now you have an extremely high end scope that is rare rare rare and could disappear at any time. A fluorite (real CaF2 fluorite not pretend marketing hype FPL53 "fluorite"). Only Tak FCT150 and FCT series and TEC have fluorite triplets. Noone else except this Stellarvue 90mm makes one. To get it in perspective - an FCT150 is AUD$13,000 2nd hand and 10 years + old, a TEC 180mm fluorite triplet is AUD$21,000. You get the idea?

Sell the ED80 and get a Tak 1.6X extender Q to increase focal length if you want to push it longer. I could be wrong but I don't think a 120mm refractor is going to beat your 12 inch dob for views of the planets. It will give a small view that could be barlowed but the image will start to break down. Aperure rules there. 6 inch APO or above is where planets start to look nice and even then a large SCT is hard to beat.

Greg.