Cannot speak on the routing, however I feel the den red carpet lounge is a total ripoff. They charge for drinks, even on international first class tickets, the food and free drink selections are very poor.

The desk at the top of the stairs is helpful for getting upgrades and making various other arrangements, especially in the event of flint delays and cancellations, they even once got me a free double cabin upgrade from status.

Overall ID say it depends on how often you'll be using the lounge, but overall I've never found the benefit worthwhile.