I was wondering if I should return to the game. I was hoping the merger would increase my chances to run Khitai dungeons but first of course I need to know if it won’t be a waste trying to search for a group non stop.
Right now there are a lot of people playing, probably even more than before the saga server, all groups I were in filled very quick but I guess the raidfinder is sucking up a lot of players because of the anniversary event right now. Still, I think it’s probably the best time to come back right now and try to do dungeon runs, especially guilds are packed with players right now, you will have a really easy time finding more organized groups in a guild.
Id say it takes around 10 to 15 minutes to find people for a dungeon, yesterday i ran a few level 80 dungeons that didn’t give any important gear, we went there only for the quests and to find people for those dungeons was easy. Veterans go there for nostalgia and to have fun while new players go there for quests or out of curiosity. I don’t think you will have any problems finding people for any dungeon or raid in this game.
And also what Force said, this anniversary event is sucking up a lot of players, so if you won’t find people for a group don’t despair, you will later that day.
You think my chance at running stuff like Pillars of Heaven are much higher now?
If you start the group yourself, I guess you won’t have much problems to fill it. If you wait for someone else, then you will need a lot of luck to find one. 
Ok a lot of thanks.