Is this alternate Draconic Ancestry trait (that grants flight) a balanced replacement for the dragonborn's Breath Weapon trait? [closed]

Question

A player with a Dragonborn PC recently requested that he be allowed to grow wings and gain a fly speed in our game. I didn't really like any of the alternate Dragonborn options that allow flight, so here is my current idea. Is this option balanced with respect to the Dragonborn as found in the PHB, with the following feature replacing the Breath Weapon feature. (Leaving the Resistance intact.)

Draconic Ancestry (Alternate): Due to your heritage, your character sprouts wings and a tail that continue to grow slowly throughout your life. If wings are chosen at 1st level, you forfeit your standard breath weapon ability as your magical bloodline instead slowly increases your flight and mobility.

1st level: Wings and tail sprout from buds on your body, and slowly grow as you age. No flight is possible at this stage, as the wings and tail are small and frail (easily concealed under normal clothing)

3rd level: Your wings have grown as long as your arms, your tail is 1/2 your arm length and must be free to balance and maneuver if flying. Your wings and tail are no longer concealable, and you must spend +20% base cost to alter any clothing or armor you wear. You gain flying speed equal to your normal walking speed. Flying is extremely tiring at this stage, you may only fly for a number of rounds equal to 1 plus your constitution modifier (min 0) per short or long rest. If you are still aloft when this limit is met, you immediately descend to the ground, and have disadvantage on any attacks or skill checks made this round. You gain "Wrym's Charge": Your wings propel you to greater speed as you charge to attack an opponent. Your land speed while using this ability is x1.5 your base, but you must move in a straight line. If you charge in this fashion for at least 20', you gain advantage on your next attack roll. This ability recharges on a long rest.

6th level: Your wings have grown to equal your height, and your tail is 1/2 your height. Your flying speed increases to x1.5 your base speed. You may fly for a number of rounds equal to 1/2 your CON score (rounded up) per short or long rest.
Wrym's Charge is usable x2 per long rest.

11th level: Your wings grow to 1.5 times your height, and your tail is equal to your height. Your flying speed increases to x2 your base speed. You are able to fly for a number of rounds equal to your CON score per short or long rest. Wrym's Charge is usable x3 per long rest. You gain the "Flyby" ability (do not provoke an attack of opportunity when flying out of an enemy's reach)

16th level: Your wings and tail do not increase much in size, but grow stronger and thicker. Flying speed increases to x3 your base speed, you can fly for a total number of rounds equal to twice your CON score per short or long rest.

Answer 1

This feature is unbalanced for many campaigns and problematically unconventional

Assessing the balance of this feature is difficult as the situational value of flight, the main selling point of this feature, depends heavily on the type of campaign you have. If you have frequent rests, a character with this feature can spend almost all their combat time airborne --- a very powerful boon, unless you face predominantly airborne enemies or ranged attackers. At later levels, that's possible even with fewer rests.

Having access to flight, compared to the usual draconic feature of breathing destructive energies, is a gamechanger. While an extra special attack is always an extra special attack, the damage dealt by a dragonborn's breath is seldom enough to kill most enemies outright, uses one's action and is only usable once per short rest. It doesn't fundamentally alter how a dragonborn character plays out. Meanwhile, having protracted and fast flight for several rounds in combat completely changes a character's tactical prospects, and starts favoring combat options that are very atypical in DnD 5e (such as "kiting" --- repeatedly attacking enemies while retreating). This is highly unusual for 5e racial features that tend to mostly spice up the actual "thing" of a character, the class. (Note that an official race with a flying speed, the Aarakocra, is not considered legal for Adventurers' League play and is often considered tricky to GM for).

The design of the feature contradicts the usual 5e design patterns in many other places as well, which is not a balance problem but can make the feature harder to understand and remember. Using raw scores instead of modifiers is almost completely absent from DnD 5e and should be avoided to reduce the cognitive overhead of learning your features. Similarly, rounding up is to be discouraged without a very good reason.

The percentage modifier to equipment costs is just odd and should be done away with; there are other weird body shapes in DnD 5e and no one else has to pay extra money for their stuff either. Seeing that it kicks in at level 3 instead of straight away, it would force characters into buying a new set of equipment if they started the game at level 1, and that sounds like petty annoyance more than an actually interesting or important feature.

Summa summarum, this racial feature is not comparable to the other draconic ancestries --- they are single-use special attacks coupled with a resistance, this is a whole separate tactical dimension for the character. I would recommend streamlining the design to be more conventional to DnD 5e, and even then urge caution especially if your group has short adventuring days.