How would you pick Tespia participants?

Both high level and low level content needs to be tested, and by appropriately levelled characters.
How would you test Episode 1 (GMS-exclusive content, btw) on a level 150 quest specialist? Even if the level caps for the quests and portals were removed (which would open the door to different bugs), if you one-hit Andras how would you be able to tell if there's something wrong with its attacks (e.g, 10 minute stun instead of 10 second)?

Such a vast amount of data in a limited time such as a week? No. This is where we decide what is more urgent, I'd rather never be able to asteroth PQ which is level what? Until 30? In comparison of being dced at something like zakum which is open content too me until level 50 to 200. Glitches such as ones that are content focused on <80 is essentially worthless excluding a few pq's which are very active and we'll be delt with anyway. Have you seen how annoying 1000 12 year old's are who lack the patience to train more than an hour? A nightmare to the ticket system, I assure you.

If such content needs to be tested than it shouldn't be all in one go, rather in segments. Make it so that only one character can be transfered at one point, such as the episodes you mentioned. To collect an array of data from 10-150 content would be impossible unless they forced players to play the game in segments. "For 1 week you will play level 10-70 content" and so on and so forth. Content that needs to be addressed is content every player will spend majority of their time, bossing, skelegons, OB4. Although the players population reflects that most characters are below 100 and only like what? 10% is above 150, the content that the 15x players use is what players at 11x can use.