I don't really want to jump into the middle of an argument and I hope this isn't an argument but rather just a discussion.
Regarding the Stealth and the changes from the "R" to the F 16HP, it is my understanding the "R" was pretty much a prototype itself, being an upgrade from the standard Stealth ala the Inter 17 and Inter 17 "R" . The standard Stealth is still offered and has a following in UK apparently but there was interest in a "faster" version and the "R" was an attempt to meet that. Then the F 16HP class evolved and the rules were set so John, IMO wisely, merely modified the prototype "R" to the maximum F 16HP specs. IMO this was probably more a marketing decision than because he felt it was "necessary" to make the boat appreciably faster. If I were looking at purchasing a new boat, right now (or in the future), strictly or primarily for racing in the F 16HP class I would probably be very intrigued by a boat built specifically to the rule. Now if there were already a bunch of F 16HP "grandfathered" boats/fleet in the area I might gravitate to one of them so I could do both.
As for slight changes in the 4.9, I also pointed out to Wouter that under the current Taipan (AHPC) rules a boat can not be called a "Taipan 4.9" unless it is class legal and measured (Are you the EU measurer Gebhard?).
HOWEVER, I think the Taipan class may want to make some provision for calling F 16HP "legal" Taipan-based boats something w/ "Taipan" in the name- ala Stealth calls theirs the Stealth F 16HP, BIM the BIM F16. These builders obviously believe this will only help their marketing efforts to have these boats associated with their "standard" one-design boats.
By the way Gebhard- Were you aware many of the Taipan cat rig boats in Aus have a totally different mast section from the sloops? I didn't know this until I had been sailing my boat quite some time. That is not an "option" that's widely known and not "marketed" here in the US. So there can be quite substantial differences between class legal Taipans right now, being differentiated on the basis of cat vs sloop rig, seems to me allowing another "version" would not be all bad, sort of like the Taipan F 18 is really just a "modified version" of the 5.7.
Just some thoughts guys-
Merry Christmas!
Kirt