So initial impressions on the d4, with comparison to i4: its definitely pretty to look at. Shows realtime time voltage and amps on each bay, so no guesstimation on what the i4 LEDs are trying to say. The clock on it I'm pretty sure ticks up for time charging, not time remaining. The amps are either 750 if charging 2 or 375 if charging 3-4.
The metal slides are REALLY nice. Maybe my i4 is just worn out, but these are great. Battery is a little hard to remove, but thats OK. I'm sure I'll get the hang of it.
Display has a decent FOV side to side, but not so much on the vertical plane.
Overall so far after 8 batteries charged and 24 hours of ownership: I definitely do not regret it. Sell off the i4 to a noob vaper friend for 10 bucks and enjoy the pretty display.