Austin,
You say "graded". May I ask what grade?
28ga's with 24"ers don't seem uncommon. Never have seen a 20ga with 24" barrels but I'm sure there are plenty around. When I was younger, the wippy 24-26" guns had a lot of appeal. Now that I'm older and slower, I find that "slow is smooth and smooth is fast" so 28" + is preferable.
At least that is what I tell myself.
If you enjoy the shorties, go for it. Now if its a gr3 + I'd look hard at it with any length original barrels in a 20ga. My opinion, no premium for the 24's, if anything subtract.
Let us know where you go with it. Love those Flues.