I trained on and raced on H3s before they were H3s - when they were Specialized TriSpokes. I raced on them as recently as last July, but after flatting all my tires I got lazy and haven't swapped one out.
I trained and raced on tubular TriSpokes for perhaps 5 years, mixing it up with Zipp 440s, 340s, and some light box section tubulars. This lasted from sometimes in the early 90s (93?) until maybe 2000 or so. I got a clincher front TriSpoke and trained on that pretty exclusively for a number of years, only taking a couple years to ride Spinergys as a show of support for a friend that worked there.
I've never ridden the carbon rim version but the standard one is absolutely bombproof, as strong as anything else out there. They are a bit heavy but they are fast once they're rolling. In a cross-tailwind they are almost unbeatable.
I found that these wheels are the fastest wheels for me when sprinting in a top speed situation (i.e. flat sprint with leadout). I think they'll be illegal for mass start racing, not sure where UCI rules are applied for Cat 3s, but these wheels have 13 fewer spokes than the 16 spoke minimum mandated by the UCI.
cdr