I'm a little late to the game but I'll cast in my two cents.

First in most large projects I've seen the clients spec the lighting and it almost always is Lutron. Typically the Lutron systems need to be programmed separate from the AV control system.

If it is a simple Grafik Eye keypad controller that I just need the serial number of it isn't a big deal.

I've found that dealing with lighting dealers is a major PITA. If they even answer the phone it is like pulling teeth to get the integration ID numbers. If the lighting is a Quantum I jack the LOE up and increase the cost by 15 points just because I know it's going to be an ordeal.

That said if given the choice I would spec a RMC3 to control a Crestron lighting system and use intersystem communications to network it to the main AV controller. It provides the redundancy and reduces labor and liability considerably.

In short I work with Lutron only when I have to and I would not at this time shed a tear if Lutron became the next Extron and died a quick death of irrelevancy.