Actually, as WhiteFireDragon (and others?) found, the phantom will fit in the QFR case with some(surprisingly not much) modification.
Pg 11 of this topic: http://geekhack.org/index.php?topic=38441.msg753747#msg753747
What are the chances the Phantom PCB has traces running where the QFR does not and has the hole located? I want to be crazy and drill a hole in my Phantom, unless of course something useful is there and I can not.
Read through WFD's post. I could be wrong here 'cause I'm at work so this is from memory
But I think there are two potentail incompatabilities.
1. hole near "shift" is moved
2. screw hole moved
#2 cannot be solved: it'd take out about 7 traces near the teensy if you drilled there. The solution is not just keep the case closed with the clips, which is more than good enough. That screw basically does nothing.
#1 can be solved by filing the PCB and relocating a trace or (preferably) sanding down the standoff. I haven't done this personally, as I run my phantom caseless (on cardboard), but it should be pretty easy and still secure.
Getting a QFR is a good choice, as you get switches, and a case that'll work with soem modification.