I am just in the process of switching from D'Addario (which performed well for me) to Savarez HT Classic 540 J Long Play ...
So far, I have the Savarez on one guitar just broken in, it took at least three or four days to stretch and stay. I am told they will last a very long time now.
So far though, I find them a bit too "snappy" if you get my drift.
Do you think that strings are becoming so specialised that the day may come that you will need a different instrument for every type of music you play! ?