Thats kinda odd to show a Toshiba inverter, with a single phase A/C motor. It seems a call to talk to someone would be worth the time.
I would have to consider the G9972Z lathe myself. The extra bed lenth, more swing, and extra 100lbs of weight to me would be worth more than a VS spindle drive.
IMHO the VS spindle drive will need some changes anyway for CNC to really have good control of it. All though if its a 3 phase VFD running a 3 phase motor from 1 phase power it may very well be able to do so. To be able to have tapping, threading or even such feactures as Constant Surface Speed the CNC controller will need to be able to know where the spindle is, and be able to control it.
Upgrades for a spindle drive are not that hard to do, and the cost can be compairable to the extra price here on this lathe. VS is nice on a manual lathe, but in CNC mode if the CNC controller cant control it then even more upgrades will still be needed if its not able to do so. I would call and talk with someone at Grizz and get the exact specs of what there using.
3 phase motors are much smoother with more torque than 1 phase A/C setups. If its a full on VFD and 3 phase motor there using that sounds pretty good. Still IMHO I would go for the G9972Z and get more machine and build my own spindle control, but thats me, may not be best thing for others.
Jess
GOD Bless, and prayers for all.