Originally Posted by
findark
Technically, nothing is lost. Practically speaking, the GM will no longer automatically receive the 1K baggage allowance, E+ seating, or BG1. However, all of these can be overridden by an agent, who will happily do so when looking at the history of the reservation.
Really, the only loss is increased hassle to get any of those things done.
Not quite true. GM loses 1k priority on the waitlist if PNR is split