I've been using MS with standard tongue and with softer of two standard springs, and DeeLuxes, and UPZ with red and black tongues.
MS is great boot, very comfy, and i would have kept them, but i cold not survive with clip-in bindings, my stomach prevents me to close bindings so i returned to UPZ.
Standard tongue of MS is equal for black one of UPZ, so there is none to compare to UPZ red one. Springs on them are easy to replace with standard industrial springs if ones provided are not soft enough.