I didn't see anyone else mention this as it might just be a "here" problem. My local REC, and I think most others in the state, requires any new motor  ten horsepower or larger to be soft started.

We lost all our bins to a storm in 2013. Our fans (10-12-15) HP were salvaged and could have been reused but the REC would not allow it. We ended up buying 10 VFD's and replacing all our larger motors with 3 phase motors.

You should check on your current site if the REC is going to require you to soft start some of your planned single phase motors. That may tip the scale in favor of the 3 phase site.

That being said, except for the initial cost the VFD powered motors are pretty sweet. We have a 20 foot auger filling our dryer that starts on lower hertz, barely turning so slow you can count the fan blade on the motor turning over. Over a period of 15 seconds it ramps up to about 30 hertz which is half speed. Never slips a belt and the amp draw on start-up is barely above the FLA when running.