Nearly all our home patients do HDF with a FMC Aqua C Uno H or previously a Purite Centurion.
Have done for about 10 years.
I was in touch with a Fresenius development engineer who also dialysed at home. He was surprised I had any qualms.
We have done HDF on single patient RO's for many years. The design of the machine has to be safe to manufacture the online fluid - you could never guarantee the level of purity of the water as things can change at any time and the dialysis machine must be safe against that scenario.