With the desert boots, it's best to buy them the same size as your chucks. I bought a half size bigger, and while they were great at first, they have a lot of give and they stretched out. I had to make more eyelets to keep the boots stable on my feet.
I went to Banana Republic today and tried on the waxed leather Saharas, in order to compare it to Clarks (though someone said they were made by Clarks?). Doing so, I realized I had never actually tried on the original. The BRs were fine, the leather creased visibly lighter immediately, I don't know if that's always the case with beeswaxed leather. I'd give these a try if the Clarks weren't available. They also had bright red suede, for those who like bright red suede...shoes.
Since it was across the street, I also went into J.Crew and tried their leather version. Though the leather looked less treated, it was also much thinner and flimsier, in fact the whole shoe felt rather delicate and not very durable. The leather was very soft, though, and it was like my foot had been wrapped up in a very comfortable crepe-bottomed sock. I don't think I'd buy these, they don't seem like they'd live very long.
I have four pairs of the banana republic sahara boots (got them on sale for 40 each) and I like them a lot more than Clark's. They have a much sleeker shape and profile, and they provide much better ankle support than clark's desert boots do.
Okay, I need some help. The ones listed on eBay, for some reason, are advertised in women's sizes. I wear a 7.5 in Chucks and I'm thinking of going for the size 9 Clarks, which would be a 7 in mens, but Clarks being from the UK and everything, I don't know if I'm doing this right. Many early posts in this thread suggested sizing down 1/2.