Hi All  I went ahead and mixed the modules and it works a treat for me.  
Hi All I have an M1000e with 4 x M6220 switches available, and I also have 2 x passthrough modules available.  I have 3 x M710 FH blades with fab A,B and C .  I also have 5 x M905 FH Blades with only Fab A and B.  Would it be ok to use the Passthrough modules in Fab B1 and B2 and the switches in Fab A and C?    I realise that I will not be able to access Fab C from the M905 blades but they are for test and dev so that is not a problem. So is it ok to mix or is that not a good thing?  Thanks  Eric 
M1000e fabrics - M6220 switches and Passthrough interfaces?