On White's (and most of these style of workboots) the toe and heel have an extra layer of leather lining anyway, so "lined" uppers really only relates to the shaft for the most part. I have a pair of Bounty Hunters (which look pretty similar to the OP's boots) with Red Dog lowers and brown bullhide shaft. I was told by Kyle that the bullhide needed to have a lining, so mine are lined. I can't say how much thinner the bullhide is, but mine are about 5 years old and normally get the most wear of any of my boots, and I think the bullhide should last 20 years, minimum. LOL
I simply can't justify another pair of Whites but when I do I want to go Bull Hide. I've heard really good things about that particular leather. Bison is another one I want. My problem is that I don't "need" any more Whites. I have three pairs now.