Interestingly, it's not solely about quality of construction. There are other issues. According to Kretschmer our modern boats with relatively flat bottoms, deep fin keels, and spade rudders hung by the rudder post only (i.e., no skeg) do not heave-to well if at all. I can attest. It's very difficult to get the Bavaria to heave-to properly in even 4-6 ft seas in 25 kt. The boat will try to turn its stern to the wind. If I fiddle with it enough I can get her to lay properly making slight progress to weather, but I don't trust it. If you cannot heave-to in conditions, not even necessarily really severe ones, you have to keep sailing which could wear out your crew if there are only two aboard and the auto pilot can't be trusted in those particular conditions.
even though Kretschmer talks about the "lack of" ability of a fin keeled/spade rudder boat to heave to, there is much more to it than that. as we know, he has his opinions about what works for him, as does anyone else who has been thru enough storms to be reasonably comfortable being offshore and knowing one is approaching. and there are very experienced "bluewater" sailors that still say a fin keel and spade rudder have no place out in the "bluewater", even though its been proven that fins and spades can be built tough enough for the task.
a fin keel is a description, but not all fin keels are the same, just as with a spade rudder, some are better/different than others.
a fin keel built for racing is deep (7-12ft) and narrow, and a fin keel built for a cruiser racer will be more in the 4-6ft deep range, and much wider (fore and aft)... the one on my boat is 8.5' long where it meets the hull, its about 3.5' deep below its attachment to the hull, and 5ft wide (fore and aft) at the bottom.... its about 15" thick at the top and 5"thick at the bottom. the boat has a 5' draft.
as opposed to a fin keel built for a racing boat.... 7ft deep, 2ft long and 3-5 inches thick....
the rudders can be just as different... so when one talks about fin keels and spade rudders being NOT not seaworthy for one reason or another, it can easily be argued...
Adlard Coles' Heavy Weather Sailing talks about the ability of different boats to heave to, and the angle at which they can do so... two exact boats of the same model, owned by two different people, may heave to very differently.
one may do it easily and the other being very difficult to balance. this can be due to the way its loaded or rigged, as the windage and the weight placement within the boat will make a big difference.
there is a lot of books, a lot of good, experianced authors, and a lot of opinions to choose from. sometimes even the experts have conflicting opinions, so we just have to keep reading and sailing so we can form our own opinion, rather than just taking another persons opinion as the facts of life aboard a boat