3-level binomial model

I computed the school-level and the pupil-level variance like that
(as described for 2-level models in MlWin manual): I assumed that
my dependent variable is based on a continuous unobserved variable
(perfectly valid according to my theoretical model). Therefore, eijk
follows a logistic distribution with variance pi2/3=3.29. So,

VPCschool=VARschool/(VARschool+3.29)= 0.17577/(0.17577+3.29)=6.4% and
VPCpupil=VPCpupil /(VPCpupil+3.29)=0.19977/(0.19977+3.29)=7.3%.

The reviewers of my paper are not sure if this is the best way to
do it. They may reject my paper and I worry because I have spent
3months!!!! writing it. Any ideas to support my method or to use a
better one?

Would an IRT model for seven "items" be more to their taste?  I  
don't think the
substantive conclusions would be much different.