We all do whatever works for us. It's easy to say that if it's in the budget, why not just get the pressing mat. On the other hand, if you'd like to give the blanket a try, what's the harm? If it works for you, great. If not, lesson learned on move onto the mat.
Several months ago, there was a thread about ecorugpads.com. They carry 100% wool pads, normally used under rugs. They are less expensive than the wool mats intended for pressing. Perhaps not as pretty, if you consider the pressing mats pretty, because the fibers are a mix of grey, white, black rather than only grey.
I'm not sure what it is about wool that irritates me, but I do itch. Even with a shirt under sweaters, I can't wear wool sweaters. But having a cover over the wool mat on my ironing board works really well for me. And because the ecorug product is so much less expensive, I bought more than enough to cover my Better Board. I lopped the extra off and put it in a pillowcase for a travel mat, or for times when I don't have the Better Board up.