The 2016 IS700z Ferris can be bought with the Briggs & Stratton 810cc 27hp commercial turf series motor or the Kawasaki FS691V 726cc 23hp motor for $500 more. If you are talking 52" deck. If you go to the 61" deck there are 3 different motor choices.
If I am correct, the B&S Commercial Turf motor is not the same as a Vanguard. The Vanguard is maybe assembled by Briggs but not made by Briggs? Not sure but they have some kind of connection.
I myself am shopping and looking at Ferris IS700z and IS2100z mowers in a 52" deck width.
I am wondering if the Briggs Commercial motor is good enough or if the Kawasaki is worth $500 more on the IS700z.
When you get to the IS2100z the motor choices are Vanguard 26hp 810cc , Vanguard 28hp 810cc EFI (+$500) or Kawasaki FX801V25.5hp 852cc (+$600) and you get bigger wheels/tires and ZT4400 hydro over the ZT3400 on the IS700....
Prices start at $6,099 on the IS700z and start at $8,499 on the IS2100z