Whether you purchase it or not depends a lot on your individual circumstances.
If you look at resales those contracts which have been extended are not selling for $20/point more than non-extended contracts. So in that respect it's not a good deal.
For myself, rather than extend OKW, it seems logical one could use that money and buy a smaller resale contract at SSR or AKV instead, and have that for the next 46+ years.