Hi there.....I have both at the moment and they are very different fish..IMO
the Sag's are very aggresive and are growing rapidly...kind of like a Midas
on steroides....they are a contender to other heavy weight cichlids...
the xilo's seem a little more fancy and the snouts on the two species are def. defferent...Xil'o more long and thin & Sag's more larger and not as long...
I like them both but I would say Sag's are more heavy weights than Xil'os and might grow a bit larger.....but the answer to your question is; they should both grow to about 10 to 12 inches for females.....and Sag's would
be bigger than xil's.....Heavy weight tank....go with Sag's....middle weight
tank...go with xilo's....
just my 2 cents......cheers