This version of Second Age has all 8 mechs available for play. There's No real downside compared to the other version, besides the Moon map being less cool. There a few tiny things missing that don't affect gameplay at all. Gaiki and the other 'secret' mech are not in this, though.
This version of Second Age has three selectable mechs, the rest are ??? Randomselects with something like a 95% chance of Excel. You might get any mech though, including the 'secret' Gaiki and other one. Not really better than the "Full" version, but it has a few interesting changes you can check out.