I wanted to confirm following:
in cross -forest on premise migration let us say migration from exchange 2007 to exchange 2010
if we use ADMT tool which doesn't migrate exchange attributes which does work for sid history and synchronize password
so how user provision is done, I asked one expert if he used FIM along with ADMT , he said he didn't so either one uses prepare-moverequst.ps1 script or FIM
1) Is FIM really not required
2) does ADMT has any limitation if we migrate upto 2000 mailboxes.