all what you did say i see it solve by only running the instance on manic solo << i did that while leveling when the auto team take a lot of time
i would say that the auto team system is wrong
if it's up to me i would make the auto team can be joined from anywhere in the city and remove the useless time and replace is with ready button
when someone want to enter with less than 4 players just click ready if all as conform that the auto system well port them to the instance
it's that easy
anyway for me i was in harry to get to level 55 , i didn't do the progress/ sub quests
for someone came to an mmo that 1 year old he wont level to max level in 1 day if he did he will leave the game in the same day 
the leveling system is good as i see (i actually see it too fast! but well the max level in this mmo is 55 so it's good i guess)
instead of fixing leveling system make a better system 
auto team system must be replaced
energy system must be replaced
add quests that make the game interesting!
change the useless daily rewards lol
on dying why only abandoning option ? where there is no option to back to the first of the instance
and add resurrection items! and again remove the useless energy system
what i can do without energy ? the only thing i can do is marketing (than this game is pointless!)
can't do quests / can't explore /search for something
i did spend 40 energy today for fashion blueprint item (if i knew it would take 40 and don't find it in the end i would just buy it from the market!)
why the mmo if i can't play in it ? no energy = close the game
and the list go on!
obviously if i continue the list i wont finish today lol! (you got the point)
anyway i really believe developers and gameforge wont listen to any of the big concerned thing for the players (cuz this would change the game) and if i made i game i would like my player to play the game as i want it to be
lol i see i did talk to much xD
Conclusion :
the leveling system it self is fine in my opinion