Lord Xia, You have more confidence than I in this type of design. I am not pessimistic by nature. However, unless they drop the unit sizes and training from the options I just don't see how they can have enough man hours to get it right.
Really, they could probably get away with the training by limiting what the training does. Anything too drastic like adding hit points and it will be a balancing issue. Once again making the units that don't have it obsolete.
I have tried too stay away from watching FE too closely. I was really hoping that they would be able to fix WoM. Now that 1.4 is essentially the end of WoM. I want to start following FE more closely. Stardock has a unique relationship with its fan base. There is genuine affection that goes both ways. I won't give up on Stardock even if FE is not perfect. For me the fact that they are here on the forums more than a year after WoM, that they listen to ideas and advice. That they usually take grief with good humor. This and more makes Stardock a rare gem among developers. Unless they drastically change their attitude or give up on themselves I will stick with them. Man that sounds sappy, but it is how I feel about it.
I am hopeful that they looked at MoM's tactical battle system. (I know that that referencing MoM is getting old but it really does apply.) It had many different units. Some were squads ranging from two to nine in size. (It has been a while so I may be off on this.) Some were single units. Some magical some mundane. You could get mithril upgrades and gain experience. I don't ever remember feeling like a unit was useless. In fact that little cheesy tactical combat mode is the standout part of a game that essentially a civ clone with magic. There were so many strategies even within each faction, that led nearly countless tactics on the battlefield. If memory serves, I believe each unit was treated separately. If a squad had six, each man attacked and defended separately. So it attacked six times. When defending one "man" defended until dead then the next picked up the overflow damage. With this design they could balance a pair of griffons etc. against a squad of pikemen etc. by tweaking the the hit points and damage of the individual units.
I believe that I read somewhere that they eventually changed WoM combat to something similar. However, even if they did, it all goes out the window with the ability to make different unit sizes. Unless the power of all of roaming single units and monsters and all of the heroes scale with the new larger squads it won't work. And if it did that the older smaller squads would become useless against the up-scaled single monsters and heroes. I believe that if designed properly the older player built single units and smaller squads might be ok but it would have to be a one for one trade off. What I mean is that a similar unit of six would have cost six times as much as a unit of one and take six times longer to build, have six times the maintenance etc. This way the player that does not research squads of six could counter with six single units. But as you can see, this is a lot work for what exactly? So that you can design your units squad size? I don't think that it is worth it. Why not just have units and squads of set sizes and if you want more, build more.
I am actually being too simple because the six single units would have an advantage because the carryover damage when a unit in a squad dies would not apply to the single units. So, they would have either eliminate carryover damage or tweak build time and maintenance for the single units, but the squads can put more individuals in a single battle ya-da ya-da ya-da..... It gives me a headache just thinking about it.
I am really glad that you brought up the "balancing issue" I have had these thoughts and feelings on this subject since the first time I played WoM.