osb mail,
When I had first heard about split-tail climbing, I had a shop Eye-splice my split-tail on a thimble, thinking the same as you, increased radius and prevention of wear.
All it did was fairly well guarantee that I would cross-load my 'biner from time to time due to the slop in the termination.
It's a beautifully done splice, on a robust thimble, but relegated to my bin of stupid-things-I-tried-but-learned-better. Fortunatly, it's a small bin.
I'm with Mike Mass on this one, can't think of where a thimble can play a part in my climbing system.
Now on a sailboat, that's a different matter.
RedlineIt