I replaced my old North sails a few years ago, but kept the genoa and had it re-stitched, which was very inexpensive. I use it for light air racing and sailing, because, having stretched a bit, it has a nice full shape. Because it was well made, and of good sailcloth, it still sets nicely. Don''t throw out those big old baggy sails without trying them out for use off the wind and in light air. The new genoa is a huge improvement when we''re working to windward in stronger winds, but I''ve been surprised at how often I still find the old one useful.
A new, custom-made, full-cut sail made with new, good quality sailcloth would unquestionably be faster than the old North, if cost is not a consideration, but the old North gives me a very cost-effective and useful choice.