Didn't get to post in this thread yet, so I'll say what I think the responsibilities of an Idea guru.
Wisdom
Able to compare and contrast benefits and cons of each card, as well as how much they should cost. Most of the analyses.
Role
An idea guru needs to decide what a good role is. A super active idea guru would voice their opinion on every card idea, but that will most often be time consuming. A less active idea guru will view every card idea, but only post opinions on the ones that catches his or her eye. An even more passive approach would be to only specifically look at cards that viewers ask. Either of these can work, it just depends on who and how it is done.
Time
A idea guru should be available at least once a day for answering questions and commenting.
Knowledge
Having a knowledge of what card ideas have been done before, how successful they are, and whether or not they are good. Able to compare previous submissions with new ideas for comparison and analyses.
Objectivity
An idea guru should not let his or her bias affect his or her judgement. No special treatment (positive or negative) should be given. All ideas and members are to be treated with the same respect.
Leadership
An idea guru should be able to sail and direct card ideas into uncharted waters, like the eternal spell idea and anti-cc for life. An idea guru should be able to help stimulate creativity among card designers.
Experience
Theory always bows to empirical evidence. The idea guru should have some experience with the game, knowing how much creatures are out on the field usually, how much quanta players usually have left over, and an idea about the metagame for balancing.
Popularity
Not a super important trait, but as all card voting is done by the community, it helps to have an idea guru that is well respected and trusted by all members.
That said OT, do you have any particular ideas for who you think would best be your successor? Has the idea that instead of an idea guru, a council of idea gurus been suggested?