I'm fairly new to BBQ'ing, so as a quick last question... When do you find it's best to use the wire brush to clean the grates? It seems pretty hard work - I had a go shortly after I'd finish cooking and it was already pretty firmly on there!
Cleaning the grates is done in a couple of different ways.
It's always helpful to put a brush on them when they're still warm right after a cook.
There are often grease drippings on the bottom side and some will use a high heat to burn this off.
I have a new grate on my 22.5" (57) and have been keeping after it pretty well as an experiment.
It's a flip up so I keep the "flippers" out of the fire when I can.
I bought a hot water heater catch pan for soaking the grate when it needs it...this makes the scrubbing go very easily after a short soak of warm water and dish detergent.
When dry, I give them a shot of cooking oil spray.
You will get "yellowing" from the smoke on the new grate...I've stopped fighting this and let it exist on the outboard sections of the grate.