Big Team Battles heavy are one of the greatest causes of raging in Halo.
Since you brought them up in Halo Reach, I will give you an example of a terrible "Heavies" map.
Quagmire. Map=Spire
There are 2 guass, 2 rockethogs, 3 falcons, 2 wraiths, 4 rockets, 4 lasers, etc.
The map was completely pointless, plus the score went up to 150 points, majority of players raged games and only got up to 100 points before it ended on timer.
Point is, heavies are terrible, if they were to put in heavies, they better make it on Ragnarok only. Which brings up a really good example of Halo 3's map Valhalla Heavies.
Everything was evened out and distributed, there were hills and bumps that would protect you from certain things. You got a wraith, scorpion, banshee, and more powerful vehicles (except gauss). If they were to put in Heavies, then my vote would only go towards Ragnarok Heavies.