I didn't test with staff, just Balrahns. I should test with the staff though 
Lesse... I don't know the levels, since they all charm T and I haven't yet taken the time to see what teh CHR diff is between Ts for level (nor do I even care at this point, halfway to 72 XD) When I did it at 70 I needed +25 CHR to get should iirc...
Code:
With Apollos:
CHR: 69+17 - Might
CHR: 69+23 - Might
CHR: 69+27 - Might
CHR: 69+29 - Should
So that one was too high a level >.> Time to find another <.<
Wearing Balrahn's + Apollo's:
CHR: 69+27 - Should
CHR: 69+25 - Should
CHR: 69+22 - Might
CHR: 69+24 - Should
CHR: 69+23 - Should
So found this one.
Without Balrahn's but with Apollo's:
CHR: 69+23 - Should
CHR: 69+22 - Might
Balrahn's magic acc does nothing :3
Without Balrahn's or Apollo's:
CHR: 69+23 - Should
CHR: 69+22 - Might
Apollo's also does nothing :3
Well, guess that answered whether or not gauge can be counted on, since it doesn't apply.
Oh well XD