IMO a lot of the gear configuration and details are not covered especially in-depth in the class due simply to time constraints. You don't have days to go over gear, you have 2-3 hours.
Many of the finer points of the gear config are best learned online from reputable knowledgeable sources or via printed material.
Also IMO it's a disservice to divers and DIR in general to simply say "go take the class" instead of taking the time to explain choices and comprimises made in the gear.
In any case, ponies are not DIR. Light canisters are worn on the right side of the waist belt next to the BP because stage and deco bottles are carried on the left.
The quasi-DIR pony method is to sling the bottle the way you would a deco bottle, but carrying the pony in the first place indicates a rejection of the diving team concept, which is one of the critical pillars to all of DIR.
I would agree that obtaining the "whole" of the DIR concept is impossible online, FWIW.