Thanks AlanF. Yes it is useful, and indicating the ratio of crop frame area to frame area, as a percentage, is helpful in judging the technical quality of what's coming from various camera/lens combinations. Many, like myself (Feb 2013 6D, 300 X2 purchase) I am sure skulk around these forums trying to get helpful information before investing $$$ on equipment.
Which leads to the next, probably oft stated point. If only those posting the pictures would include the basic camera/lens/shutter/Fstop/ISO, bird ID, etc., information then a forum like this would be that much more useful. Otherwise, it's not much different than just flipping through a magazine with a child in a doctors office.
Of course, if the data is left in the shot that's helpful but often it isn't and time is wasted checking. Just my thoughts as I reflect on why I'm presently involved, which is primarily to learn. I don't expect everyone to share my perspective.