The current system shows you your experience in a ratio. XP/min gives you a fairly accurate representation of your performance throughout the whole match, but feel that XP/round will give you an incorrect number because of these reasons:
- Rounds don’t always last the same amount of time
- You aren’t always on the same side
- You may not have played the same merc
Sure, these apply to XP/min as well, but to a lesser impact.
All in all, I think that having XP/round would not be worth it. I do think that telling the player the actual amount they earned each round (instead of an averaged number) would be a good feature.