how important is the IC stat in market samurai?

IC stands for "Indexed Content" - but does it matter?
In a word - yes!
But it isn't the be all and end all in regards to competition research, and it's a very hard metric to judge.
IC (number of indexed pages) only really begins to matter if the competing website is entirely about your niche subject.
More pages on a website means more chances to capture backlinks, and page rank. Based on google's original patents, every page creates a small amount of page rank. Both factors together result in more potential for authority, on a subject, for a website with an large number of pages.
Further - more pages means more chance for keywords to appear site wide, and more opportunity for a clever webmaster to do some clever internal linking (which can be powaaah-ful!)
Websites in the top 10 results with a high number of pages will either be general websites, or authority websites. General websites can be relatively easy to beat, where-as authority websites can be a nightmare.
Loading the IC figure seems to slow down Market Samurai a lot, and since it's such a difficult metric to take into consideration, its probably best not to load this metric until you get down into the real nitty gritty.

Wow thank you so much. That is by far the best response I've gotten on this forum.