Ok thanks again.
I didn't run any number but the logic of it seems good to me. However there's a flaw in the time.
Because the time that goes in this formula isn't the time we play but the time we're in game. So if we take 5 mins to ready up (choose start positions), we have to play only 3 minutes for the XP to be awarded and not 8 mins. When there is lots of people it's somehow common to take something like 5-6 mins to choose start pos since there are almost always people that crashes and need to reconnect, etc.
So the time the "clock" command shows or the clock shown in the bar at the bottom of the screen isn't the time considered for this formula.
Not sure you were aware of it, hence this post. Is it possible to fix it? Because currently if we pause the game say at minute 4 in game waiting for someone like jussipe to time out and then reconnect (might take 4 mins or more), for the XP it's like if we had played 8 minutes when we unpause while we've played 4 mins...