Hey Sean,
I know plenty of people simply don’t want to know what the rated input is, and are very happy that they don’t know and use this spindle in a mechanical load range where this will probably not show any issue. This has already been discussed here. Many people simply use the spindle and don’t worry about what people who know what they’re talking about say. What I say is just, I could never recommend to anyone to attach a device to a power circuit that is not dimensionated for it, already simply because it violates the safety regulations which are in place to protect you (and your workshop and home).
So you can simply say: “The chinese omit what the device is really able to draw, and I am a U.S. citizen that doesn’t want to know, so the cheap chinese VFD manufacturer and me, the spindle/VFD buyer, we meet at this point and both are satisfied”, this is what you can of course do and possibly hundreds do (that you can of course mention here). It is the same as if you say: “Yes, I know that smoking and nourishing myself with sugar is unhealthy, but as long as I don’t realize it, I will proceed.”
By the way, I don’t need to buy this VFD or to even ever have seen it to be able to apply what I know and what is only based on physics (together with information about safety regulations). It’s just that when I finally saw that they simply omit the input power and current on their VFDs, and that is the reason why all U.S. people have no concern to buy and connect them to their domestic circuits, I felt I could write a little posting about it. That’s all! 
Anyway, if you think I am not competent to say something about the matter, the 110 V 2.2 kW spindle of which he bought only a few, and why they don’t offer a kit containing this spindle: Because there is no power supply circuit in a U.S. domestic context that will be able to match the (omitted, but calculated) maximum current draw of such a 110 V/2.2. kW spindle/VFD (we are talking of at least 48 A).
By the way, regarding the 1.5 kW or 2.2 kW spindle choice, I would always choose the 2.2 kW model because you can always use less power and usually it’s not a big price difference. The 80 mm models are available for ER-20 collets which means tools shanks up to 13 mm. If you considered 65 mm spindles, yes there were problems with hairline cracks and on the Onefinity Standard Series, they don’t clear the stepper cage and bump it with their back if not slid much downwards inside the clamp, which augments the danger of chatter, while with the optional 80 mm spindle mount, all spindles clear the stepper. On Elite Series, both 65 mm and 80 mm spindles are said to clear the stepper cage.
Got to go now, was called for eating!