I guess you mean "downgrade" if you are talking about the speed.
To be honest... He is a starter Tank and its not anymore that easy to play like it was earlier, becouse of the other air starters like Medivac or Raider. The main reason for the Airship speed nerf was the easy way to start an ego game and that is not possible with Heli (if im wrong send me replays
).
And as the Heli is a balanced Tank you need a compensation for the speed nerf and i dont see any clear solution for that.
So to come to an end - my oppinion:
I understand your point and im also not a fan of these superspeed air tanks but the Heli is totally ok as he is right now.
To be honest... He is a starter Tank and its not anymore that easy to play like it was earlier, becouse of the other air starters like Medivac or Raider. The main reason for the Airship speed nerf was the easy way to start an ego game and that is not possible with Heli (if im wrong send me replays

And as the Heli is a balanced Tank you need a compensation for the speed nerf and i dont see any clear solution for that.
So to come to an end - my oppinion:
I understand your point and im also not a fan of these superspeed air tanks but the Heli is totally ok as he is right now.