The quest with a full good group on normal takes about 15 minutes. No eardweller
The quest on normal solo takes about 20 minutes.no ear-dweller
Solo on hard also about 20 minutes. Chance of ear-dweller (1.5%)
Solo on Elite up to 40 minutes. better chance of Ear-dweller. (3%)
Seems to me that although there is less of a chance of ear-dweller dropping on hard you can run at least twice as many runs then on elite. So soloing on hard seems the way to go.
Does this seem right to you?