The reason all caps is hard to read is that in caps and lower case (I can also tell you why it is called that) the ascenders (b,d, f, h, i, j, k, l, t) and descenders (g, j, p, q, and y) help form word images that can be speed read. All caps just gives you blocks of type that have to be examined closer. I don't mind a short title being in all caps but text should never be all caps. I do agree with Dick that since thread titles are usually a synopsis of the content (my edit) it is better for them to be c & l c.
Gene