Oops, I just realized I mistyped the b coefficient from Excel and JMP. I typed the R^2 value by mistake. Sorry. So, to get it right, the MATLAB coefficients are...
a = 9.384
b = 0.2592
The Excel and JMP coefficents, for the same power fit, are...
a = 9.4293
b = 0.2544
The model is...
y = a x^b
The data are at the top of my original question.