I don't have enough experience to really tell you about Melleri personality, I didn't have the greatest success with mine, though I suppose 5+ months is more than the average for people who buy WCs! Though I do my best to stay close with the Melleri crowd that does actively keep them and work with them, and even though I may not contribute to the discussions that I am sent via the Melleri email list, I am always reading... If you want to know Melleri, then visit the www.melleridiscovery.com, and register an account for the Chat nights here: http://www.chameleoninfo.com/flash_chat/chat/index.php
Back on topic, You cannot say, melleri have this type of attitude or that type of personality... They are completely sporadic. Each individual is very different.
Difficulties with Melleri? Heh... numerous. They are not an easy species by any means. If you decide to work with them, aim high but be prepared for the very possible and probable lows. Success with this species has proven to be incredibly rewarding to some though.