I think the steel-framed Compact is noticeably heavier than the alloy-framed models. After carrying one for a while, I realized that it wasn't that much smaller or lighter than a full-size model.
I continue wonder why CZ doesn't offer an full-size alloy-framed 75B -- I think that might be the best of both designs for man shooters, and would certainly be strong competition for the SIG P-series guns, most of which have alloy frames. An alloy-framed semi-compact (full-size frame and compact slide would be an interesting option, too. Some might prefer a shorter grip and a longer slide, so that would be a different type of semi-compact, but I haven't seen or heard of one of THOSE variants.
CZ has slipped out a couple semi-compacts in steel, and a forum member had one some years ago; he may still have it.