The question is not IF you will have issues, because if you charter enough, you will have issues, with small or large.

A good charter company addresses them to the (reasonable) customer's satisfaction.

Many/Most charter companies list AC/Gen as "non-essential". I would alter contract to state if what you consider "essential" (Gen/AC/chartplotter) perhaps making a notation of Refund in amount if equipment (specified) is inoperable.

I have used CYOA without issues. Very satisfied with how TMM responds to issues. Some of the bigger companies seem to have more issues that are not resolved, perhaps due to squawks not being addressed upon return?

Also customers need to be reasonable and not try to expect perfection. Be happy with good customer service and seek those companies who earn a reputation for good customer service.