that is horrible tracking. Would have expected a lot better from the EQ5 - looks like there is some irregular friction or gear problem. Could probably be fixed with a tune-up, but you must be confident that you want to do this:
http://www.iceinspace.com.au/forum/a...p/t-17262.html
advice to date has been on getting what you have to work - however, if you are of a mind to upgrade, the question becomes what would be best. To some extent, you are heading down a blind alley with your current gear.
Starting from scratch, an entry level good quality astro imaging system based around your camera would probably be something like:
EQ6 mount (or HEQ5, but only if the EQ6 is too heavy for you)
ED80 scope or similar with field flattener and adapter for your camera
60-70 mm guide scope (or maybe OAG) with QHy5/Orion guide cam
You could decide to sell it as is, but your 8 inch scope would be a good addition to an ED80/EQ6 package - it would be right on the edge of the HEQ5 comfort zone though. You could fit a low cost GSO or Skywatcher focuser - should be OK for your lightweight camera and you will probably need an MPCC as well. If the upgrade to both scope and mount is too much for one step, you could tidy up the 8 inch scope and get a new mount for it.
there would be a market for the EQ5 and 8 inch scope - still fine for visual use.
would be nice to also get the opinions of refractor users on the best upgrade path.