I would search the archives because there was a rather extensive discussion of the Luders 33 not all that long ago. And yes these are not full keeled boats by any stretch of the imagination, being closer to fin keel boats with attached rudders which means that they have none of the advantages of either a fin keel or a full keel but almost all of the liabilities of both.
Sailing characteristics wise, by modern standards or even by the standards of the day, the Luder 33''s were slow, wet and a little tender. They track very poorly, and developed a fairly large amount of weather helm when pressed. They do not hobbyhorse as badly as some CCA era boats, but tend to pitch more than longer waterline, traditional or modern designs.
The term, ''Tender'' refers to the ease with which a boat heels. A boat which is described as tender tends to have less stability relative to its sail plan than a boat described as either stiff (having lots of form stability) or described as stable, which refers to the combination of both ballast and form stability.
In my mind, there is a lot wrong with tender boats, especially when they have a comparatively small sail plan. They tend to sail at larger heel angles and be more prone to excitation rolling, and knock downs and have difficulty standing up the necessary sail area to keep the boat moving safely in heavy going.
Back to your first sentence, Luder 33''s are reasonably good coastal cruisers for a boat of that era. (A C&C 35 mk1 or mk 2 would be a better choice for less money) They do not offer very good performance and so will limit your range a bit. They are a bit deper than most 33 footers of that era and so limit gunkholing a bit. They are not very good light air boats being designed to use a huge 170% genoa in the light stuff, and so depend on very large
jibs, which are hard to deal with in a building breeze. They are not very good boats to develop sailing skills on as they are not terribly responsive. They were reasonably well constructed but would be very long in the tooth. They have a bit of a cult following and so you see good clean versions at fairly high prices for what they offer.
Respectfully,
Jeff