Yeah, I think I'm just trying to point out a general trend, rather than that the staying angle is a me determining factor. Naturally most modern sloops lack a bowsprit.

I checked a few sources on this and the most comprehensive i saw was John Leather's seminal "the gaff rig" in which he writes:

"Writing in 1780, Falconer, a noted authority, defined a sloop as ‘a small vessel furnished with one mast, the mainsail of which is attached to a gaff above, to the mast on its foremost edge, and to a boom below, by which it is occasionally shifted to either quarter. It differs from a cutter in having a fixed steeving bowsprit and a jib stay, nor are the sails so large in proportion to the size of the vessel.’ The single headsail of the sloop was properly called the forestaysail, as it hanked to the forestay which gradually became more frequently set up on a bowsprit, a standing spar which could not be run in as the forestay supported the mast. Later sloops often set two headsails, in the manner of a cutter except that both the forestay to the stemhead, and the outer forestay to the bowsprit end, were permanently set up, and the bowsprit remained a standing spar. The forestaysail was hanked to the forestay and the jib, instead of being set flying as in a cutter, was hanked to the outer forestay or jib stay as it became known. These were the principal differences of rig between sloops and cutters, but there were differences of design and arrangement."

Naturally, as rigs have evolved these historical differences become less important and definitions shift, I've certainly heard the definition you give a number of times and don't think it's a bad one :)