I agree, this is a great topic for discussion. I suggest that all contributors clarify whether they are talking about support/maintenance contracts as offered by integrators, or support (and possibly extended warranty) as offered by manufacturers, as there are critical differences.
I'm not sure we'll see so many contributions from manufacturers (we are one), as they may be reluctant to reveal what they offer to their customers (which would of course be integrators in this case).
What we find as a manufacturer is this :
Most of our integrators have annual maintenance contracts with their customers. They charge quite high fees for these contracts. We now have equipment in installations which can be up to seven or eight years old (our company was founded 8.5 years ago). This equipment is long out of warranty and whilst we support it (but have to charge for it) certain integrators are still expecting free technical support - even on-site support (!), but complain when we try to get them onto an annual support package which would cover them. Whilst they are happy to take money from the customer for support, they are not so happy to pay out some of that again to manufacturers for extended support.
I'm pleased to say that not all integrators are like that, and we find that the bigger companies especially are quite happy doing back-to-back contracts with us and their customers.
I'll monitor this discussion and will be happy to contribute further if we can get a good discussion going. It's a very important topic, as I think quality of after-sales service and support varies dramatically across the industry and it is vital for end-users to take this into account when selecting equipment and placing business.