Been using a Panasonic unit since a year and their customer service is excellent! During the first 6~8 months of its usage, the service center folks called me up thrice to inquire about its performance and issues. I was glad they did that - most of them don't.
Back at my home, we are having close to a decade old Carrier split units and they never bothered with something like this. Not that they have to knowing their units are top notch but calling up customers doesn't hurt.