Dont confuse popularity with the ability to grade...
Just because its hard to sell ICG doesnt mean that they are poor graders. Gaining the trust of collectors takes time. Dont get me wrong, Im not defending ICG...they have not proven anything to me yet.
My point is: dont write off coins in ICG holders just because they are in ICG holders. You could miss out on some nice coins. Perhaps they wont all cross-over but the whole idea of crossing-over is a conflict of interest if you ask me.
---->If a grading company wants to promote itself as the superior grader than it would be in their best interest to condemn coins slabbed by other grading companies...as not meeting their "HIGH" standards. For a true measure, I think you would be better off to crack the coin out of the holder before submitting it to NGC or PCGS.