If it is going to be a 3D specific bow, I'd use the Constitution. I have shot and handled them all and the Constitution is the most stable/forgiving platform in the lineup with a straight riser that has no reflex to it. It's settles down after your draw sequence very quickly because of that straight riser design. It also is fairly quick. I'm getting 308fps out of mine and itdrills those X rings when you do your part. The Commander is a nice bow too, but too heavy and I feel it's a bit top heavy in balance. Not really a great platform for adding stabilizers and long sight bars, etc......the Constitution is a bit faster, has more brace height, balanced better, and much lighter giving you the option to add weight where you want it for the best balance. I think the Commander is better suited for those that want to hunt with a super forgiving bow.
What 3D class are you planning to compete in? Unless your planning to shoot open class, speed isn't going to matter much anyway. As long as you are 270+ fps I would plan to shoot the most stable and forgiving bow you can get. I actually prefer the pin gaps a 280ish fps bow gives me for hunter class, any faster and I can't get the pin gaps that are best for splitting. Hunter class comes down to how many X rings you can hit, and 35 yards and closer you shouldn't be missing 10 rings due to yardage estimation. If your losing points due to yardage judging in hunter class a bow isn't really going to cover that up. The speed comes in handy out past 40 yards where the arrows start dropping a bit quicker in Open Class though.......
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A quick pic of mine in use.......
