curious as to that as well. it really depends on whether you want a fish that's more closely built to a labiatus or citrinellus. if you're looking for a fish that more closely resembles labiatus then go with saggitae. however if you like the stockier, taller bodied midas-type then go with xiloaensis like I did.
I love the xilo's and i'm not at all sold on the 9" max. size...especially if that's supposed to be TL as opposed to SL. If TL then mine have already surpassed that. I know that's what the minimal information available for this species says, but there haven't been any kept in captivity that i know of until they were imported recently so it's hard to say exactly how large they can grow. Reagan's are the only adults I have seen in person.
I got mine last march I believe and they were 1.5-2" SL. Now, the 2 bigger males seen in the video anubisscott posted are pushing 7" SL and incredibly thick. I'm expecting them to reach at least 12" SL...but then again my expectations could be off. I just don't think they'd have grown that close to their max. size in under a year.
Next time I do a water change I might have to pull one out again and see how much he's grown since last time I measured.