Click on the article above to get a good treatise on saving old wood windows. The new double-paned ones have seals that will eventually fail, some in as few as seven years, in my experience. I much prefer the look of the real, exposed muntins, that hold the panes in, than any fake ones. And you change the look of an old house with new windows. In terms of ease of operation, well, we ever open just a few windows in our house. The tool above provides the 45 degree angle desired in the glazing compound. Temperature is a factor. The oil-based glazing compound is much easier to use in warmer weather. And, if you go the $1200 route, as mentioned in the article, you will find that new, good quality, wood windows will be about the same price, if not higher. You can also find unobtrusive storm windows for the old wood ones: https://www.nosurpriseshomeinspection.com/post/windows-of-opportunity