Actually, those are very good points. I would really be interested in a game where the goal was to spend say 3 hours one night getting as far in as possible, and then transiting to 24 hour turns from there on out. Even though you can do 10-15 min turns against the comp for much of the game, obviously in MP most people want more time to think and craft their turn in the mid and late game. It would be disappointing to schedule 3 hours for "gameplay" and only run 2-3 turns that night, seems to me that the 24 hour turns get you 7 turns for the week, which is better investment.
If I wanted to host a game in that style, how would it work (I am still painfully new)? PBEM would be more complicated if you wanted fast turns at first, no? But on the other hand, if I ran a server game from my comp, then it should actually a piece of cake? Do you run the turn manually if you are hosting? I would assume if so, then there is no complication to run turns as fast or slow as need be, it would just be necessary to have everyone in IRC for the starting session, to optimize turn processing and diplomacy, to keep the pace rolling.
Anyway, someone convince me that this is a good idea.
I also prefer at least medium size/length games to a blitz, so getting a head start to the meat of the game sounds excellent.