Hi DJDD,
For planetary imaging people would go for a long FL. The longer the better. FL is not enough though and to get good resolution you need large aperture. This is why a bigger scope will give you a better view of a planet than a smaller scope. For a planet which is bright, light gathering is not a problem. A really great planetary imager would be a F20 12 inch Dal Kirkham.
Since you are talking refractors I can assume you are talking about DSO imaging. In this case I would always go for the biggest aperture with the lowest F ratio so in your case this would be the ED 102. Please note i am not talking about the optical or mechanical quality of the scopes as I dont know much about these brands.
As far as skyglow is concerned I dont think it is really relevant in your case. Any of the scopes you mentioned will under melbourne skies reach the skyglow limit after a few minutes. In Sydney I can only go for about two or three minutes before skyglow washes out everything. So i always image with a filter. In my case I use an Astronomic UHC filter.
There is a recent thread
http://www.iceinspace.com.au/forum/s...ad.php?t=28782
discussing the difference between other types of LPS/UHC filters.
To see the effect of FL on field of view (magnification) try this
http://www.newastro.com/wodaski/pick_a_camera.htm
Paul