Hmm. Here's the deal. We have the following guards
Fox
Davion
Kevin
Monk
These are the top 4 guys. Others like Colby, Duarte, Ford, Keon are lower in the depth chart, but might move up during the season, or due to some injury.
Of the 4, Monk is the only real combo guard. Fox and Davion lack size and shooting to play 2 for long periods, and Kevin lacks floor management. Even if Davion becomes a much better shooter, he can't play with Fox except for short stretches.
I agree that he plays bigger than his size, is extremely strong, and with his defense, can give problems to slightly taller players too. However, I don't think playing him at 2 is a long term solution, particularly when we have two of our top 6/7 guys already playing that position.
So, his increased minutes will largely come at Fox's expense. Might not be an entirely bad thing over the season, or when Fox skips games. However, you want your best player to be on the floor as much as possible, particularly in critical/playoff games.
So, yes. I agree that Davion will help the team a lot if he improves as a shooter. I still think that this impact will be limited to the minutes Fox is off the floor. It might be a Bobby/Bibby kind of situation, though there, Bobby was more of a combo guard, a clear third option at that position on the depth chart, and Doug was known more for defense than shooting. Here, the roles are slightly reversed for Davion wrt Kevin and Monk.