I would check out some of these groups;
as I'm a newb, I cant post URL's but google the Hallberg-Rassy Owners Association - Home Page (UK)
there's newsletters on the hallberg rassy main site
mahina Expedition - Offshore Cruising Instruction and why they chose a larger boat than what you're looking at
i'm not an expert on the type- an opinion is that the enderlein vintage hulls might be more traditional sea kindly and possibly slower. The frers hull 1990 onwards might be faster.
I like the simplicity of your era design. no inverter, generator, etc.the polyvinyl deck core is supposed to not be as much trouble as balsa. One potential problem I've heard of is the teak deck, if in poor shape can damage the underlying GRP deck. Getting new deck installed can cost big money.
There is a forum on here about inspecting used boats. Prepurchase things to look for that I think is very helpful. hope this gets you started.
Im still looking, possibly 372, 40 mkII. But the Canadian dollar has to bounce back up a lot first.
You have to join the UK HROA to get any information. My experience is that the value is low.
There is a Yahoo group for HR. You have to apply for membership if you aren't an owner. There is no cost.
The Enderlein boats are slower but not terrible. The Frers boats are just as sea-kindly as the Enderleins.
The 42 ketches are beautiful and on a reach with a mizzen staysail and a spinnaker or big #1 they are great. Customer support from the factory is very good and the colocated HR-Parts company can get you anything you need.