HI Chris, FWIW historically, the earliest documented information on the five string banjo as we know it always used a wound over silk or wound over gut 4th string. Pre Briggs book photos clearly show a wound 4th. The wound 4th continued to be used in perpetuity.
There must be a reason!
I have tried to play banjos that were strung with unwound 4ths and could not get any power out of them. When played with any force (an effect I use often, esp. in march trios) it would just slap itself dead against the fingerboard.
It is much cheaper to extrude polyester compound then to wind wire over floss so I think the cost savings, at least in part, is why a current manufacturer is offering full extruded sets. I know that a lot of old time banjo people were complaining that they would wear out the winding with frets. So it may have been in response to those complaints.
I find that with fretted banjos, by the time I wear through two wound strings there are flat spots on the bottom of the nylon strings where they get pressed into the frets and I change them all.
I am no fan of nylgut (polyester) strings. They squeak with my fingertips and clack with a thimble. I found them to go untrue due to the excess stretching. They would also get flat spots pretty quick. Not to mention the breakage (something that i have not had happen with nylon).