Thanks, Yegor. Your photos of your collection are just brilliant works of presentation. I'm struggling just to find large enough clean flat surfaces to arrange them on, and to get my books lit adequately. You both inspire me, and put me to shame.
Yeah the lettered Mister Slaughter is a tough nut to crack. A PC copy sold on eBay a few months before I had acquired these copies, and I haven't seen one since. It's the first-in-a-series SubPress syndrome.
If I come across a Providence Rider lettered I'll PM you. I haven't seen any since I found this one, I'm afraid.
I'd love to find other lettered owners to try to find matches.