Heroes 6 - Discussion

Just like in Woge, the experience will be divided proportionally among the units.

Yep, it calculates the weighted average, meaning if you add 10 swordsmen with 15k experience to 100 swordsmen with 2k experience (for example), the new unit will have (15k*10 + 2k*100)/110 = 3181 experience. In general, it's quite simple; the system is already in place. If this is developed and implemented properly, it could be very effective.