Thanks for the reply Tannin. That was the main reason for my post - I'd much rather hear about people's experience and own eyes than a computer analysis.
That's very good advice about using photographic skill to work with what you have. For myself, starting photography in the digital era I find myself too often relying on technology, not skill to take a good photo. i.e. take 100 photos, keep one. I do need to put a lot more time into the composition. I noticed some of my best photos I took was when I first got my camera and didn't have a tripod. Balancing your camera on stairs or rocks made for some great photos as the heights and angles were typically quite unusual.

Its good to know (though disappointing) that DR wont noticably improve on a better camera. Therefore, this subject is now more or less closed for me, so now my question has evolved to general image quality. Of course, at high ISO the 5D series will be the clear winner, but at low ISO will there be a noticable increase in image quality? I know this is certainly no simple question as the crop factor brings in other issues such as reach, vignetting and DOF, but as whole will it be much better?
Any review I read on the net seems to say the 10-22mm is a great lens and the 17-40mm is corner soft. Therefore I'm wondering if there's a point to going full frame? Benefits I see for myself is that with better ISO and shallower DOF (due to needing to be closer to the subject), I could shoot faster and with shallower DOF, which pretty much equates to upgrading all my EF lenses. I know there's a ton of other considerations such as bigger, brighter viewfinder, more robust, frame rate, weather sealing, autofocus, etc., but for the moment I'd just like to know about purely the image quality.

What is peoples experience in upgrading from a XXXD to an XD?