I think considering the methodology here is important to understanding these ideas. Generally I think less of 'wouldn't it be cool!' ideas, and more solutions to problems that are interactive. I think it's a problem that the Heavy is sorta a 'no skill' class. The heavy has to be smart in choosing his encounters and how to approach, but once the actual 'encounter' starts, heavy has a very low skill ceiling. It's not a problem for a class to be easy, but both with the Pyro and Heavy we see the effects of this. Sometimes both classes can shine, but mostly they're getting kicked around until those moments come. So the bolter sorta comes as a way for a heavy to get rewarded for actual aim. Aim is good because it has a very high skill ceiling. The bolter sacrifices "LOL SURPRISE" for a weapon that would, theoretically, fight more evenly with some of the classes.
The GOSPLAN is an alternative take without really changing the core heavy. With the bolter, you're play style has to be different. GOSPLAN more gives the heavy something he can do past medium range. The idea stemmed from Jarate. Giving mini crits are awesome, especially to the heavy who now becomes viable at range. Just stealing jarate has a few problems though. Lack of range, kinda shitty since the minigun has rev-up and we already have the item. First idea was to mix it with the flaregun so theres some aiming skill going on, but the rev up was still a problem. Next was to have it replace the revup as an attachable secondary fire for both miniguns. Somewhere the taunt kinda came up, to try and make it do something even more unique. Beacons are unused and making it a meter keeps the heavy 'easy' but still adds a level of resource management. It also doesn't let the heavy just fight at new ranges. Instead it can just soften bad situations.
GOSPLAN doesn't seem quite right to me yet, but it doesn't really matter since none of these ideas are going to go anywhere. Especially since none of them can be tested (which is the big thing -- no testing, no balance and modification). But I always love these sorts of thought exercises. I think Valve's attempt to give the heavy independence just doesn't come close to cutting it. Sandvich is good, but it helps heavies AFTER combat, while doing nothing to improve his sometimes surprisingly shady situationalness.
Really, any new heavy ideas should both aid him in combat where he is weak or useless, while not making him more powerful where he's at his best. Anything else needs to soften his 'best situations' to compensate (bolter). Also fun gameplay is also important. I really love situational minicrits for that reason. They're fun, promote the use of various skills and can be used to create new and interesting risk/reward dynamics. Compared to a lot of TF2 classes, the Heavy is starting to feel real 'dry' and could use some fun. Or a T.A.N.K. :3