They installed the Volta 48v system in one Sprinter so far. It is performing well but it is costly. It answers the question of having air conditioner full time in the south (90+ temps) and remain off shore power and get you through a night in the campground. The Volta will run the air conditioner and other electrical needs and charge the batteries at the same time. If you don't need that capability it might not be practical. BTW, they say nominally 48 volts but it is a 57 volt system.
The Nations alternator couldn't keep up with amp hour deterioration (input not equalling input). The Delco alternator does a good job in my estimation but and on my recent trip (just got back today) I consistently recharged my batteries in an overnight stay in under 30 minutes of driving with the Delco alternator. I watched TV, brewed Keurig coffee, and ran the Maxxfan through the night and not worry about electrical consumption.
All the vans under production still have the existing battery and Delco alternator system that I can see. They are R&Ding other battery systems. One other was on the test bench.
You can get anything you want at Advanced RV including genuine cowhide seats.