That's a pretty strong statement!
...and it's predicated on having a wide diversity of classes, feats, items, and players in each of your three games. Is that true?
I'm not him, but I am also in three games and have seen no balance problems. We have used nearly every class in the game, and allow all feats. None of the groups has a ton of access to magic item customization (the guidelines are being followed, so there's just not that much cash around in comparison to need), and the variety of player types is a little low since one game is 100% new and casual players except for me as DM. Also, the highest level group is level 10. So my *feel* for game balance only goes that high at this juncture.
There have been one or two WOAH moments, but they've been relatively bland in comparison to the sorts of WOAH moments I've had in 3e.
For example, the battlerager vigor fighter is really, really durable in combats against lots of weaker foes.
The warden felt weak at level 1 because she didn't pick toughness and almost everyone else in the group did, creating a mismatch with her expectations: she expected to be the most durable in the group, but with a low armor class and hit points about equal to everyone else, she was not. Until she advanced a level and took toughness and gained 7 hit points for leveling up.
I feel like our fey pact warlock is weak, but part of that is his lack of tactical play. He took powers that let him do some crazy hit and run attacks, but he's so worried about getting hurt that he never actually does them. Tactically, he should be moving into melee reach and flanking with the warden, gaining prime shot and flanking bonuses, then protecting himself with eyebite and teleporting to safety if a cursed foe dies. In practice, he hides in the back line, doesn't get prime shot, doesn't get flanking, and ends the day with all of his healing surges and without having done a lot.
Our paladin has some issues with athletics, acrobatics, and being grabbed. She's a charisma paladin with a 12 strength, so her athletics and acrobatics are pretty terrible. She recently got grabbed by an icy grasp cast by a higher level spellcaster. We realized after a round or two that she could only make a high enough athletics check to escape if she rolled a 19. With two rolls a round it eventually happened, but that was pretty lame. And of course the spellcaster just tried to re-grab her. The party (this is my highly tactical group) stopped that from happening by dazing the spellcaster and walling him up in a wall of fire, meaning he had to choose between spending his single action to leave the fire and survive, or to sustain the grab. He chose life, and then ironically the paladin killed him.
I can also imagine some ways to build characters that aren't very good, such as a greatweapon fighter who doesn't take any defensive or healing class abilities. But overall, I haven't seen any meaningful problems yet.
There are one or two I anticipate at high levels, and I'm a "expertise is a must-have" believer, but that's my experience so far.