Mode changes (Voice/Performance/Multi) can be done by sending sysex messages to the Motif ESR.
Here are the sysex codes that work for mode changes here:
Multi F0 43 10 7F 00 0A 00 01 03 F7
Performance F0 43 10 7F 00 0A 00 01 01 F7
Voice F0 43 10 7F 00 0A 00 01 00 F7
GM F0 7E 7F 09 01 F7.
My Motif is setup to boot into Multi mode since its the most common mode I use.
Multis & Performances can be selected by bank/patch change from Sonar instrument definition
Patch[8128]=Motif Rack ES Perform.
Patch[8129]=Motif Rack ES Multis
[Motif Rack ES Perform.]
0=1-Cyber Step Co SEQ
1=2-9Ft.Hammrz Co SEQ
2=3-Dynasty Co SPLIT
3=4-HyperComp Co SEQ
4=5-SambaMan Co SEQ
etc
[Motif Rack ES Multis]
0=Multi:Sequencer
1=Multi:Flip Hop
2=Multi:Hip Hop 1
3=Multi:Hip Hop 2
4=Multi:Disco
5=Multi:Funk 1
6=Multi:Funk2
etc in the appropriate parts of the INS file should work as it does here.
There's a copy of my default Motif ESR INS file here
http://www.filefactory.com/file/17242c/n/Motif_Rack_ES_ins It's reasonably standard, though it has stuff added for my PLG cards and a couple of other non standard things like Multi 0 is a blank multi I use with no patches loaded, no FX etc for controlling everything from inside Sonar). The INS file also has all the drum note names defined. Use it if you like or just pick bits that are handy.
(No responsibility taken for the inevitable typos in the INS file).
HTH