Hi Kaz,
I can only comment on my own Jeanneau yachts 51, bought from new, and my personal experience and opinion.
The Jeanneau Yachts range was always marketed as a notch higher than the Average White Boat with the intention of bridging the gap between the low volume boats like the Oyster, Hallberg Rassy and Amel brands to name just a few.
But like all high volume mass produced boats you get what you pay for!
Did they achieve their aim, considering the level of sales and the new models coming out I would have thought the answer is yes.
Yet, it is unfair to compare these boats with other larger boats build by the low volume builders, as at the time of purchase a similar Hallberg Rassey would have cost at least 3 times the price.
I must be quite unusal as I upgraded from a Hallberg Rassey 37, also purchased new, do I regret the move, defiantly not, we all know, there is no such thing as the perfect boat and that each is a compromise, even though the Hallberg was a much better built boat the design and style of the Jeanneau Yachts 51 is more suitable for my current needs, Mediterranean summer cruising.
The 51 was the smallest of the range which enabled me to enter this class of boat, unfortunately they have now stopped making the 51 and are concentrating on the larger boats in the range.
As a husband and wife crew, comprising of a single handed captain firmly under the control of a catering admiral, the 51 is easy and rewarding to sail. At anchor she is the perfect summer home.
It is too early to answer your questions on mast stepping as the range is not that old yet, however, common faults on my boat can be placed into two categories, design issues and quality control.
Design issues:
Firstly, the expanding davit problem is one of water ingress around the tubes, fixed with a small drain whole in the rear deck lockers, that allow any water to drain down to the bilge, while extended, I found copious amounts of vaseline around the bottom of the tubes solves the problem. Secondly the ceiling panels are held up in most places with velcro and eventually they start to fall down, I believe this is due to the ply boards not being sealed and the humidity start to warp them, just sufficient for the velcro to part. An easy solution is screws with plastic covers. Neither of these design issues are a deal breaker.
Quality control issues;
This is where I find most of the Yachts 51 problems, which over the last 4 years I have had to address and put right. Each boat build will have its own teething issues and it would be silly to list each one as it would only be appropriate to one boat.
But the question is knowing what I know now, would I purchase another, and the answer is yes.
p.s. My boat was fitted with an 11Kw Onan generator from new.