I love it ! I've used all those malts in various IPAs (except for the chocolate rye which is for color) with good results. I have some Mandarina Bavaria and am dying to use it soon - heard good things. It's a fruity Cascade offshoot supposedly. So use it like Cascade - ie., flavor/aroma additions. The Hull Melon are another even fruitier Cascade offshoot, same uses.
I totally agree with the 1:1 + BU:GU for IPA (I actually often use 1.2:1, just me), so I would use it for whatever OG you target - ie., if you target 1.062 as your OG, then shoot for 62 IBUS, etc. I remember one of the Stone 'Enjoy By' IPAs from a couple years ago used all new German hops, one of them the Mandarina IIRC and it was excellent. And I've used Mt Hood, which is a German Hallertau offshoot, for years in American hop blends. I say go for it - I'm likely doing something similar soon.
EDIT - I'm picturing something like: 70% Pils
25% Pale Munich
5% Caramunich
1.062/70 IBU
Magnum - bittering
Blend of Mandarina Bavaria/Mittelfrueh/Tettnang - whirlpool, dry