All of our appliances were installed by our contractor. I guess it depends on your level of confidence in their abilities.

Regarding warranties, I haven't heard of them being voided but I have heard the warranty may extend out longer if you use their certified installers.

My contractor did mine , including Thermador built-in fridge. We never even thought about having someone else do it.

There is no clear answer here. It is a judgment call. Have you read the warrantys for all the appliances you are purchasing? Have you downloaded the installation instructions and presented them to your contractor? Has he installed those appliances in the past? Does he feel confident he can install them? Can he have his carpenter there to make any adjustments? Is he installing the kitchen cabinets?

As for the appliance store, it depends on how many of the brand they've installed, which installer you get etc.

Our contractor's electrician and plumber installed the appliances originally. They only do high end work and know what they're doing. But I still provided a book to them with all the installation sheets.

When I had to retrofit my built in fridge, I bought from a highly rated local dealer. I hired his installer to retrofit the fridge as it was years later. My fridge was not the brand the guy usually works on but he did an ok job. The fee was very high.

Installation fees tend to be very high for appliance installation. It's a place where you want to have all the info on hand, supply it, be present during the job and don't try to get a cheap job because you might get lucky but you might need to pay more in the long run to address lack of experience.

I always do it myself. The guys the appliance stores send out are not to be trusted to either do it right or not mess up some other part of your job. Half the time they have no relevant skill or experience at all. None of the typical installations are very complex or difficult, especially if you are willing to stoop to reading the instructions (something I've never seen a paid "installer" do-- so what if there are a few parts left over?).

Read your warranties.

Read your reviews of the appliance store you were thinking of having do the installation. Some of them are very good at installing certain appliances only. Be sure and look for this.

If your GC is willing to give you a guarantee, he may want to be responsible for the installation. You need to consider this.

If the GC is doing the installation and is not giving you any guarantee, you need to find out how you will be able to make a warranty claim for any of the appliances he installs.

I have to agree with the comments of reading your warranties.

I know when we sell a high end appliance the warranty can be extended by having a authorized installer who was trained at the factory.

The biggest mistake I have seen is the venting of the hood. If you have purchased a high end hood you need to make sure the venting installation is 100% correct. I have herd of unhappy clients who bought good hoods but the installer used improper venting material and wrong size ducting. When this happens your hood will not work properly and be louder than it should be. This is something you may not even notice or pay attention to but I am warning you please beware of a bad install.

After spending $25,000+ on appliances no way was I going to skimp on the installation. Especially when some like with the Sub-Zero offer extended warranties when using a certified installer. Since the OP said they have high end appliances this is not IMO a place to skimp!

My question is how much is a boatload of money? The cost for my Bluestar setup was $299. for delivering/install and making sure everything was tested per the manufacturer installation guide. I had installers that knew my product. Worth the money IMHO.....

Robertson - who is sending their installers to the factory for training?

All the way to Europe for Gaggenau and Miele and Asko ?