I own a Nonsuch 30C and feel compelled to toss in my 2-cents.
First, it's a pleasure to see Arthur (Bear Away) involved in this thread. The man has a truly respectable amount of knowledge of the Nonsuch.
I purchased Lazybones (formerly Port O' Call), a 1980 Nonsuch 30 Classic, in 2003 from the original owner through Jim Eastland (Eastland Yachts) in Essex, CT.
Cosmetically, the boat was rough and the original Volvo
MD-11C was hard broke. So, in October of 2003, I began a refit
of the boat starting with a re-power that was agreed upon with the owner. After all was complete we departed Essex in April 2004 for a trip back up to East Greenwich.
I had made this trip before on my friend's 30 Classic which got me hooked on the Nonsuch.
Since then, I have comfortably sailed this boat in all conditions, including a Nor'Easter, and never looked back. Contrary to what most people think, the boat works upwind just fine although admittedly best on a reach. Additionally, I have single-handed this boat many times with no issues. The most important thing is that the Admiral is comfortable in all conditions.
You can find some (but not all) pictures of upgrades at:
LAZYBONES 30C 77 1980 Photo Gallery by Nonsuch Photo Galleries at pbase.com
Most recently had Lazybones painted with Awlcraft 2000; what a beautiful finish.
Bottom line is that I have never found the need to look for other boats. We love our Nonsuch and if we were ever in the market for another boat it would be a Nonsuch 33.