Differences between making new units (upgrading already existing), and geting units personal exp :
1) upgrade unit =higher stats,maybe new talent/skill. Need new unit models, textures, graphical part of game for move/attack/use skill ...
2) unit exp=higher stats,maybe new skill. Need 2 text files,graphical part for using new skill.
It`s faster with unit exp, since those text files work for all units in game, and making new units (upgraded version) you need to make special files for every unit individually.
I`m not saying new units would be bad idea, but i meant to make tactical part of game a bit demanding. You buy units then upgrade them and with no work have stronger army, but with unit exp you need to win battles, and use all units to get exp/lvl`s to reach new skill to get stronger army. It`s more commander like
I say this because i dont like kiting, so ppl who kite around get all locations checked and then return to start with dragons (or what ever they want to play) and start first island with imba army. Geting uprgaded units will only make it easier in those cases.
For unit exp even with kiting there will be need to fight some battle before geting skills for all units you use in army.
All this talk my about less work for making new game i`m only thinking because all thah wasted time 1C invested in Royal Quest, instead making great games KB2, KB3 ...