I am experienced at playing live games and 10 min/phase should surely be enough.
I regularly play live Classic games on webdiplomacy.net. Gunboats are often 5 min/phase and press games often 7 min/phase (an option we don't have here), though 5 min/phase and 10 min/phase for press games also happen regularly. These games are playable, though you have to make decisions quickly and don't have much time to ponder on your strategies.
An advantage that vdiplomacy.net has over webdiplomacy.net is that many maps here have the IA map. With use of the IA map, you can enter orders much quicker than without.
I sometimes play live games with friends on vdiplomacy.net. The latest game I played was
gameID=30710, a 10 min/phase press game on a map for 9 players. We had plenty of time to talk and to enter orders. The IA map helped with entering orders quickly, but I don't think was even necessary, because if you make quick decisions, you can do a lot in 10 minutes.