shared some ideas below, feel free to correct me or add something. and, if smth different comes to my mind later, I edit this post. I'm afraid that this one'll resemble Jes's post about rumors but it's better than nothing.
you won't get any rare with lens + 1000keys. being 1000+1000 is just a part of the quest. in this way, you'll get 20kk exp for 1st step, 10kk exp for 2nd.
if I got correct, you can open the chests up to 10 per day and they'll give you 200k exp per chest. and, nobody else can open the chest is already opened before for a one day.
about x2 exp times,
we may go to new swamp together on double xp time and these mobs seem better than redbones in terms of exp (60k/min at swamp, 40k/min at redbones in worst-case scenerio when I'm alone without double exp). plus, if we can finish the quest in 2,5min (bet we can because of bust), we can just get 4kk because of warping. after that, Knowledgeable Tree will warp us to "Graveyard Indoor" (or you can say Caretaker's house), and suppose we can go to swamp again in 3-5min (granted that there not be noob). so, it can be done again and again if we have ingredients.
for those who wanna try assassin sets,
with str:100=89+11 agi:115=87+28 vit:61 int:1 dex:1 luk:65 and bull helmet, assassin shirt, assassin pants, assassin gloves, assassin boots, heart of isis, ruby ring and enchanter's amulet (optionally) you can get those below,
bull helmet instead of cat ears increases the dps to 980 from 815 (with ruby ring), ruby ring instead of topaz ring increases the dps to 977 from 916 (with bull helmet). so, you can see str is more important than agi for brawlers. and ofc, you may notice the difference between two dps (980-977), if you equip bull Helmet right after cat ears you'll get 980. who doesn't want to skin a flint?
you can have higher dps than any equivalent warrior in terms of stats but as you know warriors have higher double damage and crit. advantage. so, I think warriors will be one step ahead on that. and, you can do leveling in gy with 1dex without being blind but this evasion still doesn't make you untouchable enough (with 99+28 agi either). besides, obviously you'll take higher damage than warriors when they hit normal if you do not use shield (def'll be 81 for brawlers, 100 for warriors). but eh, I guess we can't say warriors are the winners by landslide.