Well after some searching I found the disappointing answer to my issue.
Mainly down to my own ignorance having just started the process of transitioning to Premiere Pro and partly down to the way XML and the XML Export options are dealt with in Premiere. Anyway I had assumed that like Final Cut the Final Cut Pro XML Export option would work in a similar manner and that is to exported XML was for the selected sequence only. I had made this assumption in part as other export options such as Export Media are selection specific and not the Project Globally.
All this means that it makes for a very awkward workflow in terms of using colour grading apps like DaVinci. Yes there are great tools like those produced by Red Giant for grading within Premiere but personally I find them slow to use compared to a dedicated system with a proper control surface and whilst great aren't as versatile as a dedicated app in my humble opinion.
I guess the other reason it caught me out was simply down to the fact that in so many instances within Premiere if something is global by default such as importing another project you get the option to select the project or a sequence and a similar approach is implemented in Dynamic Linking which is great.
I think it would be great if Adobe would implement the option to just export a single sequence to XML for round tripping purposes and obviously keep the full project export which I am sure for many will be useful. It would also be helpful if the implemented XML Version 5 as this should allow use of other third party XML tools such as Atomic Duck's excellent Media Copy 3.0 to get a report or copy files associated with a project or sequence based on a universal XML file. As well as powerful and extremely versatile round trip options.