Well, Shareef has career averages of 19.9 points and 8.2 rebounds. I don't remember Horry having any 40/16 seasons lately.
That's the part I'm not comfortable with either. Scola and Horry can coexist just fine, because Horry doesn't need a ton of minutes in the regular season, so as soon as Scola earns them, he can play them.
Shareef would definitely want a good chunk of somebody's minutes, and I'm not sure whose minutes they are. I suppose they could be Devin Brown's, but Shareef complained about playing SF in Portland. If it means we don't bring back Horry and/or don't bring in Scola, I'm not sure he's an improvement.