I've been using the 18k palladium for several years now and love it.
It's much more malleable, (not softer!) and works very nicely when
fabricated. Because of the higher melting temputure, soldering with
18k hard is easy. Brightcutting is a joy with it. The metal is
darker than 18kni white (but no yellow!), and we rhodium plate when
we finish a piece anyway. Some of the patterned wedding bands we
make cannot be made in 18k ni white (less malleable, harder, as in
less bendable.) whereas the palladium white works great. Palladium
white should last longer and wear better than nickel white because
it's a denser metal. And yes, it does cost more.
Jones & Jones