My Horizon is tuned to a B and I still use 9-42...
Don't get what people complain about when they go on about tension problems :s
I mean, yeah they're looser, but they're still fine to play - I'd be much more frustrated with massive tree trunk strings, that require crazy high action, than some slightly looser strings..
Oh - And D'addario, incase anyone is interested, invested £80 in a 25 pack a couple of months ago - the box is funky, but the strings won't come out without a whole lot of effort...