Teknow to the rescue!
I tried the link list node initially, but couldn't get it working properly, (Back to re-reading the expresso help files for me I guess) then I changed to the Object List node because I thought I had the 2 nodes mixed up. Still no success, the logic you used in the Xpresso LinkList file is what i was trying to achieve in the examples I uploaded, but couldn't get the correct set-up.
Your first two scene files are fine if you're only using a few objects, your example using the time node was also very helpful, i hadn't considered that approach.
But the 3rd scene file is by far the most practical for updating things on a larger scale though, thanks for you input :)