I well items with all my characters for items to sell (Junks for like 1-10 fg), might get some upgrades or other items for others. However, my main reason for welling is for Prof gain for Weapons / Charms. It sounds stupid, but it helps a lot.
Just use ML gear on last hit as many people stated, this is more likely for side drops as you can tell if the main item dropped in the Well will be good.
Example from experience (in group)... Kalms put in a level 45 Earth charm into the Well when group is only level 35, he got 1 hit killed and we just about lost the entire party, we bridged in higher level characters to kill off the Monster, the charm is 165% EE. Oh, my guild mate is using it to this day ever since Andy gifted it.
As for 200ee items, a person found a 2xx ee armor, you can check the HC Sexy Drop thread, think it was like 2 or 3 weeks ago.