Hi Pepin
Early last year I sold my 2001 Stealth R for £4,000. It had been well looked after and the price didn't include a trailer. However, it had a good pedigree winning the F16 Nations Cup in 2006 (with a F16 mainsail which I now use on my new Stealth)
As for the Stealth R to Stealth F16 developments, there have been quite a few since 2001 and I wouldn't be sure of the exact dates but you have certainly already mentioned the main differences. But there have been some more subtle differences in regard too thicker wall thickness of the beams, wider beam seats, stiffer and maybe lighter carbon masts, fully laced tramps, lower bridle fixing points to hulls, carbon mast rotation arm and carbon spreaders to name but a few.
However, If I was you I would get as much as I could for the Nacra, sell one kidney and buy a new Stealth <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />


MP*MULTIHULLS