I have been using Kalium Hybrids and Daddario XL's for the past couple of years, and wanted to try an alloy 52 string. Since I am a big Gary Willis fan, and love his 90's tone, I figured I would give Progressives a try.
I am glad I did. They are very different that the Kaliums. They have a lot more low end information with a smother upper high mid, not much zing, and a really nice bell like top end. They also have all the low mid growl of XL's but more upper mid growl. Their response is very tight and percussive and they really respond to your touch.
The feel is very smooth like most nickels. The tension is good, and balance/feel from string to string is very uniform even though string to string tension differs.
I have been using the stand XL 170-6 set and the Kalium .130 six string set, so have become accustomed to lighter strings. With the heavier Progressives i have not noticed any increased effort in plucking, but I was able to lower my action quite a bit.
I have had them on for about two weeks now, and am really enjoying these strings.