For me, it's always been annoying to change all my men every time which change the military reform.
After months of battles I find myself having to send away all my veteran legions to alter its military reform.
I wish this thing would change in EB2.
I would like to keep my veterans through military reforms.
Of course, using the different skins of armour upgrade.
So we can be grouped 2 or 3 or 4 units into one.
Only need the units are similar to each other.
In this way:

leves -> roman skirmishers
rorarii -> roman skirmishers upg 1
velites -> roman skirmishers upg 2

accensi -> roman infantry
camillan hastati -> roman infantry upg 1
polybian hastati -> roman infantry upg 2

camillan principes -> roman heavy infantry
polybian principes -> roman heavy infantry upg 1
post-marian cohortes -> roman heavy infantry upg 2
imperial cohortes -> roman heavy infantry upg 3

camillan triarii -> camillan triarii

polybian triarii -> polybian triarii

praetoria cohortes -> praetoria cohortes


Than 6 units instead of 13.