G'day and
Dez.
It sounds like you have already given this some thought and I agree with you that a dob to start with really is the way to go. That way at a later date when you do decide if imaging is for you, you can mount it on an EQ6 mount and start the slippery slope of astrophotography poverty.
As for what size dob there are a couple of things to think about; the 10" would be suitable to mount on an EQ6 with a (light) guidescope for imaging (pushing it a bit though), the 12" would be really pushing the limit. The standard newt rings for a 10" scope will not fit a 10" dob (a GSO/Bintel dob has a larger diameter) so you will need to get some made up. A dob won't come to focus with many cameras used for imaging so you may have to make a few "minor" modifications to the tube and mirror placement eventually.
The LX200 is a great scope but you will need to put it on a wedge to image with it and it is not a light scope to be lifting up and down onto a wedge. Alternatively you could get a 12" (or 10") tube only and mount it on an EQ6 (pushing it) or a Losmandy G11 or similar (still very weighty for the mount). The Celestron range of OTAs are lighter than the Meades which is another consideration. Imaging at these long focal lengths (even with a focal reducer) if very challenging.
How about this for an option. Get the 10" dob now, then later on down the track get an EQ6 and an Orion ED80 refractor (or similar) and image through that for a while. Once you have the hang of that you can then look at mounting the 10 onto the EQ6.
Anyway there are a couple of options or you.