Another quick update:
I found a problem that was causing a small number of players not to show up on the list. It has now been fixed on the live version and should take effect immediately.
There was also an issue with the caching which was causing it not to be cleared as often as it should have been in some circumstances - this would explain some of the "the list doesn't refresh often enough" complaints.
And finally, I have come up with a method that may help weight higher value targets to the top of the list. I have a build working and I am hoping to push it live next week.
I should disclaimer this with a couple of things though:
Firstly, it will take some time to propagate as it needs people to be attacked in order to figure out what they are roughly worth.
Secondly, the system is still time based, so people in your range that haven't been attacked are still going to be on your lists. This will just try and get the high value / active players back to the top of the list sooner.
Finally - it could all just explode. I won't know until it is tested under live conditions.