Thanks to everyone for their comments so far.
I don't see any problem using a well designed platform for any of my Dobs, both home made and commercial. In fact, I'd point more of the issues at the ability of the platform to do the job than the Azimuth bearing of my Dobs mounts to be a problem.
Had a look at the Equatorial Platforms site thanks Mark. Look nice and with exchange rate probably the best time to consider buying, but still will cost a bit when shipping is included, and some GST/customs expenses.
As some of the guys here have said, there are plenty of decent photos taken using these platforms. Actually, I am more interested at this point in time just to track an object so I don't have to keep nudging the thing and get the most out of the view. However, down the track, it would be nice to have the option of tracking accurately enough to do long exposure photography.
I will also check out Telescope and Astronomy to see if there is any progress there.
Thanks for the comments about different mount types. eg split ring, but the Equatorial Platform should be able to be configured to use with a reasonable size range of Dob telescopes, so would seem to be a reasonably flexible approach. Being able to adjust +/- a few degrees for lattitude would seem enough, unless I think of dragging it up north which isn't likely to happen.
If I build one, it will have to be strong, stable and not too heavy. Is that asking too much
oh, and cheap! Well, looks like I need to research it more and look into building one. CN here I come!
Barry mentioned about the cost to fabricate a proper mount, but fortunately for me, my time doesn't cost me $150/hr. But if someone else wants me to build one, then, yeh, I'll charge them $150/hr.
I'm an amateur, at least at these things, so I would gladly help someone else for free.
Nick