There is a constant stream of posts on the internet that talks about the 'math hole' in 4th edition DnD. The problem is this: The monsters get a +1 to all of their attacks and defenses at every level but the players get a complicated mess of bonuses that add up to closer to +.9 to all of their attacks and defenses at every level. This means by the time you get to high level the players miss an awful lot and get hit constantly - it doesn't mean the players can't win but it does mean that fights take a long time and the feel of the game is very different. That is the objective difference. The subjective difference is that it sucks.
For example, my defenses at level 1 are:
At level 30:
So since the monsters get +29 to hit they are a relative advantage of
This is completely nutty. Now, if we assume that I take all three of the 'mandatory defensive feats' which improve my Fort, Ref, Will by 4 each and also take a feat to improve my armour by 1 then it looks like this:
The armour difference is fine, but the fact that I devoted the maximum amount of resources possible to defence and I still get hit significantly more is awful. In particular most monsters are going to be hitting my Will defence on a 2 anyway so I sure won't waste the feat. It feels to me like when you spend a feat to be better at a defence you shouldn't be hit on 2+ on a d20 by any random dude. The problem with the armour defence is not the discrepancy of 1, which is close enough, but the fact that it requires a bizarre kludge where magical armour is allowed to be masterwork when it is very powerful and masterwork gives either a +3 or +6 bonus to my armour. If you are going to use a bizarre kludge can't you at least hit the actual correct number?
One good question is this: If we assume players buy every single defensive feat should they then be tougher at level 30 relatively speaking or should they be the same and we just assume that everyone has to buy those feats? I think feats that are mandatory to keep your basic defenses in line are poor design but at least the defensive 'mandatory' feats are actually reasonable in power level unlike the 'mandatory' offensive feats which literally make your character 30% more powerful. The defensive ones are more like a 5% increase in overall toughness which is quite reasonable.
Our current strategy in my group is to give everyone a +1 to hit at levels 5, 15, 25 and to ban all the 'mandatory' offensive feats. Here are some options I was thinking of for defensive bonuses that fix the math problems in similar ways.
1. At levels 9, 19 you gain +1 to Fort, Ref, Will. This means that people with good stat spreads who spend all 3 defensive feats will end up with slightly better defenses at high level than low level, but only by about 1. People with bad stat spreads like me will end up right on par, again assuming buying all 3 feats.
2. AC is trickier because light armour wearers need to get a random bonus of 3-4 from somewhere and heavy armour wearers need 7-8. I think for AC we can just force people to take a feat to get their AC up to snuff so we should aim for 3 and 7. My idea here is that everyone gets a +1 to AC at 5, 15, 25 and heavy armour wearers get an additional bonus at 6,13,20,27.
These are of course a little bit kludgy but since the basic math of the system is off we need to find some way around it. Ideally of course we could just increase the scaling of the +bonuses on the weapons, armour and necks instead but that would require a rewrite of the costing on the magic items and would end up giving players a greater bonus to damage than they current enjoy with magic weapons - lots of complications crop up when you start rewriting the bonuses on magic gear.
The absolute simplest way to do all of this (but which doesn't match the numbers as nicely) would be to give everybody a 'special super power bonus' of +1 to all defenses and all attacks at levels 5,15,25. Secondary defenses would end up a bit higher and you would need to give heavy armour users twice the bonus to their heavy armour but it would overall be very easy to understand and work with and would do away with the need for masterwork items entirely.