It wouldn’t be as good as AWD, as the center differential it typically either full open, or full locked, power distribution slider locked at 50?. It would be as good as part time 4X4 as it would also have a low range, and selection to lock the differential, but with added cost, materials and weight. I believe many Toyota’s, and Land Rovers were equipped as such.
It was also used in several Jeeps. Particularly the Grand Cherokee and earlier Grand Wagoneer.
While it was used IRL, I don’t really see what it would add to the game in terms of design choices, considering it’s used for pretty much the same purpose.
There were even cars IRL which had either part-time or full-time 4X4 depending on the transmission choice. The FJ Cruiser for example had part time 4x4 with the automatic transmission, and full time 4x4 if with the manual.
Isn’t full-time 4x4 the same thing as an AWD system because it has a center differential, compared to part-time 4x4 which has no central diff?
EDIT - Okay, so full-time 4x4 implies an AWD system with a high/low range in the transfer case. Yeah, I can see that being of use.
Actually it would add to the design choices… right now if someone wants to build an off road vehicle its pretty basic. If you want to build an all weather 4X4 you choose either the AWD which is great for all weather, but not so good for off road. Or you keep with the 4X4 which IRL is pretty crappy on ice, and mediocre on wet roads. (either rear wheel drive, or it likes to go straight or sideways in 4X4).