I'm always amused that whenever someone considers an IGH, an early thought is "what else can I put in this instead of the factory specified lubricant?"
Since 1986 Sturmey-Archer has specified (and used at the factory) NLGI #00 semi-fluid grease.
BTW, ATF, which relatively speaking isn't a great lubricant, will ruin the seals on a 7, 8, and 11-speed Shimano hub.
My thought when I built my Nexus 8 commuter bike was "what lubricant can I put on this to avoid disassembling it every 5,000 kms?"
So I when I disassembled it for its first service drilled & tapped the hubshell for an oil port. Used ATF since then, never disassembled again, just change 15 ml ATF every 5,000 kms. Zero problems after 10 years/50,000 kms. Adjusted the cone just once. Still works like new.