I'm not sure on whether you're referring to the original MG Freedom or the MG Freedom 2.0 that came out back in April of last year. You also just listed most of the SEED kits with a backpack. The GAT X-103 Buster and GAT X-207 Blitz are not back heavy because, get this; they do not have a backpack. They have thrusters on their back, but no backpacks. To compensate for their heavy backs, Bandai decided to include a stand in all of the MG kits (except for the Justice, Sword Impulse Strike Noir). This includes, the Freedom 2.0, Strike Freedom, Aile Strike Ver. RM, Strike Rouge + Ootori Ver. RM, Strike E + IWSP, Destiny, Strike Full Package, and the Launcher/Sword Strike.
This version of the Freedom 2.0 will instead include what it seems the Action Base 1 instead of the standard SEED stand. I understand your ill feelings towards SEED but claiming that most of the SEED kits are back heavy is kinda wrong dontcha think? Especially when most of them come with a stand inside the kit. You also get the most out of a kit with an action base because it can perform an "action" pose.
Nonetheless, this is a pretty good deal. The kit retails for 4,845 yen, which is about $43.19 USD (not $63.00 MSRP. Seriously, it takes a quick google search). This kit has to be one of my top 5 kits of all time. The engineering is incredible which in turn, creates a very posable mobile suit. Just watch out for the hip pegs. They will break if you are rough with your kits. Thanks for reading this essay.