Teresa:
You wield a mean cane, JD.
LOL. That reminds me of something Asimov once said, about the day when someone talked to him about the "Golden Age" of 1970s sf, he would rise from his wheelchair and beat them with his cane....
Science Fantasy is practically a contradiction in terms. Speculative Fiction really applies to ALL fiction, and so is redundant.
On the first: hardly. It is a long-recognized subgenre, and includes works by writers as diverse as Jack Vance, Andre Norton, Lin Carter, Michael Moorcock, J. G. Ballard, Harlan Ellison, C. L. Moore, Henry Kuttner, Rod Serling, Charles Beaumont, Joanna Russ, Richard McKenna, Roger Zelazny, and James Tiptree, Jr., to name only a few.
On the second: technically, yes. However, it is also a label that Heinlein originally gave to SF back in the 1940s, and which was picked up on by Alfred Bester and other writers of that bent; championed by the writers of the "New Wave" (including those who were later adopted into the movement) as much more fitting for stories which were light on the overt scientific elements, yet in which they played an integral part (the story would not work without the influence of these scientific -- or pseudoscientific -- aspects, including their effects on the mores of the cultures presented. Again, writers who specified that they wrote "speculative fiction" included Moorcock, Ballard, Disch, Merrill, Platt, Burroughs (W. S., not E. R.), Michael Butterworth, Russ (again), Tiptree, Jr. (again), Ellison (again), Bernard Wolfe, Josephine Saxton, Pamela A. Zoline, etc. (again, to name only a handful). Nor were these simply fictional writers... they were also often acute critics of the genre(s), with both a keen understanding and incisive grasp of the literary canon and theory. Given the long history of its use by such as either a subdivision of the broader realm of SF, or as a separate but related genre, I'd say its legitimacy has been more than established.
Therefore, I maintain that SF is a better term, as it encompasses all three either separately or together.
And, to once again relate this to topic: This ties in with what I was saying earlier about the preconceptions about SF and why the average audience member (and, sadly, many younger readers in the field as well) have a sort of "tunnel-vision" approach to the genre, when -- like fantasy -- it is an enormously rich, complex, and fertile field that extends far beyond the limits all-too-often imposed upon it. Again, who among the usual audience would even think of, say, Moorcock's Cornelius stories (especially such pieces as
A Cure for Cancer, or those in
The Lives and Times of Jerry Cornelius, or
The Adventures of Una Persson and Catherine Cornelius in the Twentieth Century) as "science fiction", let alone "sci-fi".... Yet these are very comfortably accepted into the genre in written form.
And then there's always the original broadcast version of
The Lathe of Heaven....
However, science fiction fans already have a strong pedantic reputation, why make it worse by arguing over the terminology of the genre?
It isn't being pedantic. The terminology itself has a meaning, a history, and a host of associations connected to it. As long as "sci-fi" remains associated in the minds of so many with "the three B's" (see above), use of the term for all SF reduces all SF to that level of hackneyed balderdash. And, whatever fans within the genre have come to feel about the term, in the general laity, "sci-fi" is still chiefly synonymous with poorly-written, immature, utterly fantastic (in the negative sense of the term) drivel with no relevance whatsoever to either literature in general or life... and that association makes it very important to draw a distinction between the
Buck Rogers/
Battlestar Galactica (original series) sort of tripe and, say,
The Prisoner,
The Lathe of Heaven,
Charly,
2001,
A Clockwork Orange,
Gattica (with all its faults), or
Solaris....