That they might leave out the APU for weight may be true, I don't know. None of our Classic 60's (well, except one) have an APU and we have gotten by ok. But, the XR's all do have one, and it really is a needed device, in my opinion. The electronics just drain so much juice out of the batteries, you have less than 20 minutes or so before things start blinking on you. If you get to some of the airports we go to that just don't have a GPU, setups are a problem. And, we do go to plenty of smaller fields.
I think it would be a serious step back to have an aircraft with that size and capability, and not be able to provide the owners with A/C or heat because you are in podunk city. Not what they are paying for.
But, not my ball to run with,,,,I just drive the bus.