I use the mix 26 4:1 UnUn with 85 feet of wire strung up like an inverted V with a 50 foot counterpoise on the ground below the antenna and have gotten good reports on 80 and 40 meters. I used this antenna which I call my "Field Day Special" this year for Field Day and made over 300 contacts on 80 through 10 meters as well as some DX from Europe before FD began. The inverted V arrangement does not take up too much space if your yard is small and it is easy to set up for portable ops as well.
I have also used the 4:1 UnUN with 25 and 31 feet of wire as a vertical wound around fiberglass "Squid poles" for portable ops with good results as well.
I plan to string up 85 feet of wire as an inverted L at the QTH since my yard is very small.
All in all the mix 26 4:1 UnUn has been a great addition to my kit.