I´ve called the number a few times to select a seat.

Main benefit: No hold times. Especially if you don´t have any status with LH this service certainly improves the overall experience.

Agents also seemed friendlier than usual, but my sample size may not be statistically relevant.

It would be interesting to know whether the dedicated F line has "specially trained" agents and whether they´re capable / empowered to fix issues during irrops etc.