I agree to both your proposals.

Alderian's proposal is more reasonable in my opinion. Alternating phase lengths just overcomplicates things.

I've had exactly the same thought as TBag. This would be a great pull-down option.

I don't think anyone is actually extending the rounds for no good reason. In non-live games I often save, but don't ready, according to my real-world schedule. For everyone's comfort and to give everyone a margin of tolerance, and (not incidentally) to give new players more of a chance to get in and take over a CD, I would keep the system as is.

option in pull-down at adv. sett. and infoormation-line at new games

No.
For simplicity's sake I submit another agreement with the opposition.

When everyone is ready the game moves on. Whenever the players require less time between orders they can ready orders quicker. And when they do require time they should be given the set time in accordance with the simplest possible principle which is the current one - same time for each phase.

The pull-down option... well, ok... but it still seems to me a quite superfluous feature.
The secret behind why the idea is mistaken is this:
It forgets that the main obstacle for moving on with the game is Real Life.
It is based on the assumption that you need less time to think and negotiate for the retreat and build phases. But most of the time people have does not go to the game at all, but to Real Life, so the difference in how much time you need between the phases is only very fractionally dependent on what kind of phase it is.

For "live" games the idea does make a lot more sense... and this is also the rule for f2f games as I understand.