You argument to get rid of the "garrison" unit is great, that is until you end it by asking for a new infantry unit and smash your own reasoning for getting rid of the garrison unit.
Here is a better proposal: Each division has a "Garrison" province assigned (sort of how fleets have bases). After you change it, you need 6 months to change it again (to avoid gamey-ness). If the unit is in it's garrison province, it gets a Logistics Wizard type bonus (-25% supply).
Not only is this better, it is actually historical.
As to the question of troop echelons, I agree that this needs to be represented. HOI2 has a priority toggle, which sort of handles the idea, but it isn't perfect. The new equipment system opens up more possibilities. And the echelon concept is perfectly historical.
I would propose a simple ranking system 1-3. Soviets have like A-D or even more perhaps, but forget that. A 1-3 system is perfect.
The way it would work would be like trays. Current equipment goes to rank 1 by priority, and spills over to lower ranks. Recent equipment (current-1) equipment goes to rank 1 if needed, then rank 2 by priority, and then spills over to rank 3. Obsolete equipment (current-2) goes to ranks 1 and then 2 if needed, and then rank 3.
This would be the best way of implementing an "echelon" system as it solves the issue of directing equipment, and doesn't require adding pointless unit variations.
I can only acclaim your idea about garrison province, and supply -25% as this is basically the same as I said but more practical, this is true garrison duty in designated area. Developer should consider this.
I am not sure is 6 months period to long ? Maybe 3 months to change it again? But that's not so important.
About echelons, I agree with your view its logical.
I would add to it even more:
When thinking about 2 class of infantry I was influenced under old approach in many HOI mods so far. Yes this I could have thought beter.
It thought mainly on mobilization waves. First echelon will be regular mobilization of man in its prime age for soldier duty (18-45 years) and second echelon or "class" will be, usually as a last option, infantry of men 17-60 years mobilized(with 18-45 excluded since not available anymore), but now that you put your perspective on the table, maybe a manpower not divisions should be actually classified as this.
How about to implement manpower not as solid form, but a mixture of class 1(prime age privates 18-45) and class 2 (last option mobilization to young and to old). So standard best-fit division will have 100% class 1 manpower, while, lets say in last ditch survival of the country a it could have predominantly class 2 infantry (example 40% class1 manpower, 60% class 2 and sum of it makes division manpower statistics)?
There will be manpower pool of both class 1 manpower and class 2 manpower. Here I should say that for Airforce and navy only class 1 can be considered.
As for grund forces, player could choose, of course if country has enough class 1 manpower to make all ground divisions of this man. However some countries(historically Germany in later war period) there will be an option to make mixture of class 1 an 2 manpower, with result of lowering fighting statistics of division to maintain divisions in combat status, or player could choose, and here we came back to garrison, to assign majority of available class 1 manpower for Frontline divisions and class 2 to garrison and occupying divisions
Thank you very much for your debate, I edited my OP in order for people who see it first time get more definite picture.
