I do have a question on balance vs fig count. I believe the blurb says 4-15 figures a side, is this geared at similar numbers per side, so a quick game is 4-5 figs each and a longer game is 12-15 figs each? Or is it 'power level' (for want of a better term) based, so you could have 4-5 'investigators' with great equipment and powers facing off against an Evil Villain and his 14 mooks?
There is a universal points system so that each figure is costed based upon its attributes, special abilities, arms, armour and other equipment. This system is included in the rules so that people can design their own teams as well as using those listed in the book. There is a common and clear arithmetic progression in the points for the different aspects of a figure ensuring that the cost reflects the capability and lethality of each figure.
So you could indeed have a small team of real heavyweights up against a much more numerous team with one 'boss' and a gang of 'minions'. However, even the toughest figure can be taken down by weaker enemies if they can work well together. There are no GW Deathstar Stompy Independent Characters of Death in these rules

Having more than two players, and thus more than two teams will extend gameplay, as will the choice a depth of the scenario that you play and the landscape you play it across.