Having my router running nicely, and considering some jobs that will have it running for many hours a day, I'm considering upgradinbg to a HF spindle. The Chinese water cooled ones , as sold by HomeCNC, keling , Tigertec and others are especially tempting, at $900-1600, including the necessary VFD. Does anyone have any experience with any of these spindles? I"m especaially worried about the possibility of electrical interference between the spindle and the steppers from the inverter.