Glad you've fond a "work-around" for the whistling E with the Kaplan string !
I agree - it is nicer under the fingers, being wound, although, that doesn't bother me over-much with what are already guitar-hardened callouses
My only issue with it ( the Kaplan NWE ) is that I find it a tad "tonally un-matched" to some other strings - I haven't really taken the time to try to find a "match" - but I kind of suspect that a different A may well "lead into the kaplan E" better than the G, D and A I currently use...... but, for me, that's an interesting distraction, I'd rather just play and not get involved right now!!!
I seriously recommend not copying my mistakes. D'oh -
Please make your own, different mistakes, and help us all learn :-)