Well DL thanks for coming on board with more good choices for mallets, I had no idea about some of the suggestions, but all are good in my book!
The second part to your thread is very interesting and I would like to tell you a story that might answer some of the questions you are asking.
To begin I would like to travel back a few years--At UCV when all the Historic buildings were reconstructed,(about 1960) part of the work on each building was to reconstruct the window sash(es). Good C select pine was used for the work and as the years rolled by about every 10 to 12 years nearly all had to be reconstructed eventho they were well taken care of and painted etc it was a yearly maintenance headache.
Now to expand on this my father about 1946 built a new barn and from the pine logs on the property, he had constructed 6 light sash for the barn at a local sash and door factory--that is now 64 years ago. These sash are still in use and going strong.
I put this question to some experts in the field, and their reply was that the use of mill run pine (heart wood) and the yearly White washing with lime and no exterior paint, lead to their longevity--the lime actually kept the rot at bay, and the bare wood could take the weathering.
I hope this information finds its way to the restoration experts manual because it sure works wonders, and I hope it answersyour questions