It's more complicated than just giving Suggs starting job at expense of Harris.
Harris is ultra anemic player, one of least productive, box score vise, starters in nba.
But thing he can do is shoot, and thing he provides even when he is not touching the ball is spacing.
Replacing 43% three point shooter with 33% shooter is noticable and steep.
And once you clog paint with Banchero, Suggs and Fultz, and your second most reliable shooter is Wendell, you are wracking whole team dynamic as your center, who is most comfortable around rim, now needs to pretend he is Mo Bamba for sake of other players and driving lines. And by design, Banchero will face more double teams than before ,since now both guards aren't really treat to punish you from outside.
Maybe, maybe you can get away with it in regular season, but that starting 5 will get exposed in playoffs in most painful way possible.
Things where Harris excelles, Suggs can't follow.
Catch & shoot. Harris 43% - Suggs 34,8%.
eFG off catch 64% vs 51%
pullup 3s- 45% vs 30%
pullups in general 42% vs 34%
If you think those numbers aren't far off, those co-relations are very similar between Steph Curry and Jordan Poole, so you decide how close they actually are.
Fultz and Suggs simply don't compliment each other at all. Fultz off ball is already problematic, Suggs on ball is problematic, Suggs off ball is learn on fly, both off ball and you might as well not play with "PG" at all and replace them with Harris and Jett or Ingles.
I tracked down game where Fultz and Suggs played together for several min ( vs Heat, at February ) and it's mostly lot of this

Fultz ghosted in corner, Wendell should be screening for Suggs, but Suggs doesn't have it in him to play off ball and run around Wendell off curlt for shoot because that's unnatural for former playmaker
Second half of same game and same problems continue

Suggs is told by Banchero to use drag screen to go on perimeter, but he once again doesn't use screen. In picture it seems like he does ,but again, he doesn't make hard cut, rather leaks out and wants for ball. Because that's what playmakers do. Hold ball. Any normal shooter ( Strus in literally play before this one for example) would do hard cut , go around Mortiz and step into a 3. Instad, Suggs gets flatfooted, leaks near half court ,and doesn't get ball. ( Possession ends in some awkward off ball foul on Mortiz that lead to 2 FTA due bonus)

And last, again, it's simply impossible to understand why is Suggs standing where he is standing. if he moves to his right, he will stand in path of Fultz and block him, if he goes right, he is clashing into Mortiz. And this is situation where Magic have 6'11 Isaac, 6'11 Mortiz and 6'10 Banchero on floor, with tallest Heat player being 6'5. You think anybody on Magic recognized gapping missmatch adventage?
Only tengable adventage of playing two playmakers is to have two players who process game quicker than anybody else. Suggs simply isn't that guy. He moves like point guard, but is such a disaster when it comes to decision making that he hurts your offense no matter is he on ball or off the ball. And paired with Fultz those problem just get so much worst because Fultz is aposlute no treat for opponents without ball, and on ball, everybody knows he is two tricks pony- penetration or middle range pullup.
Suggs whole problem is that he has one gear- go balls to a wall with brain on autopilot. If he can't slow a f*** down and start thinking what he is doing on offense, it doesn't matter will he play PG, SG, SF, PF or C, he will never be starting level player anywhere.
as for game, if anybody cares, we were up near 20, lost in OT but on surface Fultz and Suggs had nice box numbers, however, when they played together, it was mostly just messy.
Life is what happens when you're busy making other plans. -John Lennon