Team Covenant had an excellent discussion on this on the Gencon podcast; basically, Legion seems to be a miniature war game that you may break out to have a good time and get some cool minis to ogle at and get into the hobby aspect, but not for the competitiveness necessarily seen in other ffg games.
IA simply does a better job with the 65 min tournament rounds a fills the tournament itch. I can see this as a competitor to the Runewars player base. Of note, Gencon had a 16 player Nationals for Runewars.
So really both have there place.
