for ESX in service mapping are u using ESX URL as a triggers point.
Service Mapping -Maps your application and Its Running Components...So ESX URL running on which servers /DBs /Web Servers etc. VM are internally managed Objects by Vcenter ESXi.
a given ESX may have >100 VM on it correct.
In Service Mapping lets say ur Mapping for ESX setup these VMs are not playing any role Impact wise. At this point of time i can only say it may need a deep customization.
Regards
RP
