Graham, this looks awesome!
I'm very happy to see that Slimcoin is able to intrigue developers.
By making your work public you can count others in for testing!
I'm already cloning your repo and will try to compile slimcoind on Ubuntu and Raspbian.

As the main dev position is still vacant (and as far as I understood "Mr E" he doesn't want to have that), you could think about taking that position. It looks like your work is an application for that position
I don't know how many people are still actively following the Slimcoin development, but are still running nodes.
As development might sooner or later cause a hard fork, it will become important to make sure the "network" is aware of that development.
E.g. bter.com still offers trading of Slimcoin. In case of a hard fork they need to update their wallet.

I'm very excited to see such a progress at Slimcoin.
PoB to secure a block chain is just too interesting to let Slimcoin end.