It was explained to me the 6 port gas tube was a durability upgrade. Truth, no clue, but I'm sure those 6 ports can exhaust the air out of the gas tube faster when fired, it also acts as a redundant in case one or more ports gets plugged.
The ergonomics of the altered charging handle, this I've wondered about, but from a manufacturing stand point, it kinda makes sense. Ak's packed this type handle, Albania had Aks from Russia, they started their own Ak production in '74. So would it be that far fetched to say it was done for simplicity sakes, what's easier to machine, the SKS or Ak charging handle?
The dual door butt plate, another modification, makes keeping up with an oil bottle and cleaning kit easier, at least in the designers eyes.
The stock and handguard, maybe, "no your countries won't fit if captured"
or their magic crystal ball said in the future, a company named Tapco
would make stocks/handguards for all the others. So, lets make an oddball stock/handguard combo so ours don't get desecrated with plastic.
Lord, please forgive me for that jab!!