I think it does not hurt too much to have /index/ and then also /product_info/ in the url. It is just not pretty nor as short as it could be.

If I look at my top ranking competitors with commercial carts, I see only short precise url's, no unnecessary stuff. I think the shorter the better for human and SE.

I understand if you don't want to make more code changes ( I assume you talk about code in your mod, not the core). I am just trying to give you feedback that would make this mod par with what is out there for other leading carts.