One complaint of Hero System is that its to easy to break game balance.

I think this is a valid complaint. The problem is that a system that isn't easy to break just feels to limited in how and what kind of character I can make.

So for me the trick is to develop some forms of measurement to keep things in perspective and have a way to communicate with the players about their character.

Some players for example are inclined to believe that the real point cost of any ability or power in Hero System (HS) is the true measure. They believe that limitations are inherently making the power less effective. The problem is they are wrong. As the HS clearly calls out that Active Points in a power really define its power. Just because I can only use a power during a full moon doesn't make the power less effective. It just contrains it to a certain circumstance.

Combine this with the fact that the last dice of effect in a power is much more powerful than the first dice and you then add another complexity to the game.

NOTE: this is based on the fact that any first dice of effect will go straight against someone's defenses. For example a 1D6 entangle is relatively easy to muscle out of by the normal human but a 2D6 2PD/2ED entangle is very hard and a 3D6 3PD/3ED entangle is nearly impossible. So the effect of that last dice of effect is the difference between getting out and not.

To help players in my fantasy campaign I've created an algorithm to help them bench mark their abilities and powers. This has been a very real tool for us to help in evaluating the characters. Warning: This does take a spreadsheet or other tool to manage.

Spell Level
A Spell/Power Level is determined using the following formula:

For spells/powers of 60 Active Points or Less:
Active Points of the spell / 10 with the result rounded to the nearest whole number

For spells/powers whose active points are greater than 60 the level shall be a non-linear progression:
(Active Points / 20) * (Active Points / 30) with the result rounded to the nearest whole number

I hope this helps if you have trouble figuring out the relative power of things in HERO System.

NOTE: the value of where the non linear progress starts in this ruling should be related to the power level of the characters in the game. In my campaign the characters are supposed to be pretty powerful so 60 seems like a good place to put the non-linear progression.