As an aside, look at the NON EB thread. Almost all checking in at T-24 have been getting mid level A boarding passes. I got three with highest A 51, so would have wasted $30 if I did EB on all. Espcially since the first on can save seats for the others if only 1 gets an A pass.
I will not use EB unless I am on longer flight (+2 hr) AND can not be around at the T-24 time to check in.
Of course, over time if more use EB and puts those that check in at T-24 into the higher B group, I will modify my criteria.