Simmons idea makes some sense if you were guaranteed to get Lebron, Bosh, and Johnson. However, I really don't think Johnson wants to leave and Lebron is 50/50 at best. Bosh can be had but there will be competition from Miami and New Jersey. I mean look at NJ's situation. They already have a center and pg and a solid SG in CDR. You add Bosh and the number 1 pick this year and suddenly NJ is a team stacked with talent.
In sum, the odds are that you are not getting all three and if you don't get all three, then trading Gallo makes no sense. I keep Gallo and go after Lebron to take on Harrington's role in the offense and then make a decision regarding Lee.