It covers my entire tank bottom, with the exception of about an inch on the left and right sides.
I'm thinking if I want to go with a RFUGF I probably should just buy a new UGF plate anyways and set it up so I just use one powerhead in the middle. Right now I have the uplift tubes on the left and right sides and I think that's a bit of overkill on a 40 gallon tank. I'm just a little reluctant to do so because I just transferred my fish from a 20 gallon about 3 weeks ago and I'm worried I might stress them out too much by moving them again.