Tommyeats - Good question on the cheese in the middle at The Iron Horse. They cook them long enough so the inside gets done and the cheese still resides in the middle. But, if you want a medium rare burger, I'm thinking they'd have to put the cheese on the top.
There are two types of commercial char-broilers - radiant and ceramic. One uses a sort of triangular shaped protective metal sheath that sits over the gas burners. It seerves two purposes. First, it keeps the grease from dripping on the burners and clogging them up. Secondly, when the juices of the product drip down, it creates smoke and that drifts back up towards the meat and helps flavor the meat. But, it is not as flavorful as a ceramic type. High heat, quick cooking, good texture, but not as flavorful as the ceramic version. The radiant ceramic broiler is rated at a very high BTU capacity.
A griddle burger has a different texture and taste...But, if you use great fresh meat, it's still a great burger..Just different. The debate goes on and on....
The commercial ceramic charbroiler is more like what you find in most homes...there are u-burners underneath these brickets. The big difference between the home version and the commercial version is the BTU capacity and the size of those u-burners. There's a huge difference. Again, you're getting tremendous and fast heat to the meat. The ceramic charbroiler not only costs less to buy than the radiant one, but it flavors the meat better. The downside is more clean-up, cleaning the u-burners (sometimes they have to be sandblasted) and replacement of the brickets.
Both of these pieces of equipment are different than what's called an upright broiler. These are found in a lot of your top steak houses like Peter Luger's. They give off even more heat, but there is no char-broiled flavor per say. The heat is generated above the meat instead of below it. These are monster broilers which is what you need for a big, thick steak. Their BTU ratings are higher than either of the units I previously mentioned. They broil faster. Yield a crusty exterior you can not get a home.
I have no idea what the other famous steak houses are using to broil their steaks. Could be any of these three types. I do know Peter Lugers use to use upright Franklin Chef broilers. I'd be surprised if they've changed. Maybe they've changed brands to say a Vulcan, but not the type of broiler.
They both require a commercial hood and ansul system.