Hi Dan,
I've always been stuck by the comparatively small percentage of vanes I see on American cruising boats, relative to European/foreign counterparts... Admittedly, my sampling is primarily confined to the East coast/Bahamas/Caribbean, where most American boats are simply motoring down the Ditch to those destinations anyway, but even in last year's Caribbean 1500, the percentage of vanes was quite small...
Probably several reasons for that, as others have already pointed out... The switch towards much larger boats, and those of higher performance, for sure - Mark, Paul and Justin are correct that vanes aren't very well suited to boats capable of quick acceleration and surfing... I've always thought the inability to easily interface vane steering to a GPS waypoint, unlike can be done with an autopilot, is a big downside, as so many people these days appear to be sailing in that mode... The increasing popularity of walk-thru/sugar scoop transoms is another reason, making the mounting of most vanes very problematic... And, of course, the number of cruising boats now carrying dinghies on davits, and fitted with stern arches and cockpit enclosures, I'm seeing more of that stuff every year, it seems...
Nevertheless, for a modest slug like I sail, a vane is definitely the way to go in open water... Probably the single best piece of gear I've ever fitted to my boat. Incredibly reliable, steers with more power the more the breeze and seas come up, beyond a certain point there's no comparison with the performance of my tiller pilot... I would never want to do a long passage single or short-handed without my vane and tillerpilot w/ spare drives, but that's just me, thinking about sailing my own boat... Electronic autopilots have become significantly more reliable over the years, and it's been quite some time now since I've had a real problem with one on a delivery...
Perhaps as much as anything else, I'm simply enamored by the whole IDEA of my vane... I love just sitting in the cockpit, watching it work... It's an incredibly elegant blend of creative engineering and art, and represents what sailing is all about, for me. Making use of nature's forces alone, with no dependence upon anything else beyond the effects of wind and flowing water... I think you really need to experience the use of a vane over a period of time to fully appreciate the thing of beauty it can be, and when sailing close-hauled with everything dialed in, it steers my boat far more effectively than I can... Which probably isn't saying much, I'll admit... (grin)
Best regards,
Jon