Curious. For home use is the Blackstone appreciably different from a quality grill with good griddle plates or the Weber with the gourmet bbq system and a griddle insert?
I have a cast iron plate I used with my Weber for a couple of years, trying to get the wonderful crust on my burgers that you can easily achieve with a Blackstone.
It didn't work well for me.
There wasn't enough room to cook more than a couple burgers. I had to put my hand over parts of the very hot grill to flip the burgers. But the biggest problem was that the grease from the burgers had nowhere to go when it came off the burgers.
The cast iron plate I had had a drainage canal on one side and the fat drained as designed into it. But if I wanted to get the cast iron hot enough to get the crust I wanted, by the time I had to flip the burgers, there was a lot of grease in the canal and it was spattering all over. Enough to burn my hand some, get on parts of the grill and it was worried enough I left I needed safety glasses to finish them up.
Trying to put cheese on and then getting them off was hazardous.
They didn't come out great and the cleanup afterwards was painful. Was not a fan of bringing a heavy cast iron plate full of grease into the house to clean up (and neither was my wife).
I saw Weber had a more of a flattop griddle like solution for sale and almost bought it but a friend already had it and hated it because it did not fit perfectly over the grill and he had to deal with really hot temperature coming over the edges. And it was a royal pain to clean up/dela with grease.
The Blackstone has a slot in the middle of the back wall for the griddle designed for you to push grease, debris, etc. into as needed during the cooking process. It is really easy to keep things clean during cooking and when you are done cooking and it is cleanup time, it makes that relatively easy as well.
I still prefer my steaks cooked on the Weber but the convenience and consistency of the Blackstone is hard to beat. I like ribeyes and the fat in them can start a flareup that can mess up a steak on the Weber quickly. I find I need to be close to the grill at all times if I am cooking a ribeye on the Weber.
With the Blackstone, things are a lot more controllable and predictable. And cooking stuff like vegetables, fried rice, bacon, eggs and hash browns is not possible on the Weber and really convenient, especially on a hot day when you don't want to fire up the oven in the kitchen.