I don't cut grass for a living and I really can't imagine a huge difference between different types of mowers. When I think about it in simple terms, you have a motor turning blades at a certain rpm with blades and it cuts what it comes into contact with. The only variables are the blades and mower deck (assuming the motor is powerful enough). Is the Scag deck that much different from the Kubota deck? I don't know the answer, but it must be if it indeed cuts Bahia that much better.
I have had three different Kubota mowers (mid mount mower on small tractor and finish mower on medium size tractor and now the zd221) and they all cut Bahia what I consider very well, but again I don't cut grass for a living so I really don't have experience with other machines to make a comparison.