I've recently just gotten back into Rival Wings, and realized how crazy and fun this mode is. However I've also noticed even compared to Frontlines out of the Garo event the queue's themselves are much tougher to work with.
Revival Wings is a fantastic group that helps get games going, but I really feel that there should be some official support in terms of a Roulette just designed for the maps. Throw in some EXP, Wolf Marks, and the daily tomes and I feel like it'll be a new breath of life into the game.
Hidden Gorge is a lot of fun and it'd be great to play with more people as the mode is much more balanced then Frontlines making team plays way more fun.