I have both products, use them both regularly, and would recommend either (or both) products to anyone cooking on a kettle.
That being said, I always use the GrillGrates for steaks. When I was cooking at home on my 22, I would load up a full chimney and, when lit, spread them out between my two (empty) baskets. Depending on whether you use them right-side up or upside down, you will either get great grill marks or a "flat-top" style steak.
On my 26, I can use grates and still have some room as a warming area.
BD