If you are at 225 at the dome on a WSM, your top grate will be about 15 degrees cooler, and the bottom grate will be another 10-degrees cooler, for a total difference of 25-degrees dome to bottom gate.
That puts your bottom grate at 200-degrees. That would be harder to hold steady, IMO, and could possibly give you some smoke management issues.
I aim for 250 to 275 on my WSM at the dome. That gets me in the 225-235 or 250- 260 range down where the meat is.