I had an old Vixen Geoma ED80 .This scope has the same body and specifications than the Opticron Imagic..
This is a very good scope,very good indeed,although the final quality of the image would be determined by the quaity of your particulat unit..My scope had a bit of Coma,or slight misaligment,but the image was excellent all the way to 45X,or well passed 30X in any case...passed this point it got a bit soft,but totally usable.A few times I even boosted the image with my binos in the field and got good enough images to get a really distant identification.
Color correction was very good,as you expect from the best ED glass..the scope was lightweight and waterproof and the eyepieces selection ,huge..
This scope compared VERY well with the Kowa 824 I had at the time,and with Nikon´s ED50 that I also owned at the time..both the Kowa and the Nikon were proportionally Sharper ,but only marginally..
I also had the Pentax PF65 ED ,not at the same time,but almost ,and I think the GEOMA was slightly better,..it definitely showed a better star Test and held magnification better.
I am not totally sure the Geoma and Imagic models are the same scope with different brand name,but knowing the similiraties of other Vixen and Opticron models,and the exactitud of the body design,I am more than inclined to believe this..
The Geoma had an ED and a NON-ED versions,not sure If the Imagic is the same or ,as I mentioned,Your scope is an ED version.
If the scope is Non ED, then YES, a smaller ,60 or 65 mm ED scope would be better ,granting more clean and contrasty images, that You CLEARLY be seeing as superior and that You would remember being superior..
If You have the ED version a side by side comparison would necessary to notice the difference and maybe not worth the upgrade unless You really want to get something DEFINITELY better ,and as Perry said,at a cost...
Take Your scope to an optics shop and do the side by side test,or dont hessitate to ask people you meet in the field to let you do some comparisons,and then decide