Still stuck thinking about relative advantage, so I'm going to flesh that out a little bit more. Also, I'm home sick and a little bit loopy, so roll with it. Dragon Age seems to be proving a decent example of the benefits of a relative advantage type of system. You level up a fair amount over the course of the game (about 20-25 levels) and gaining levels can gain new abilities, but the increase in effectiveness comes out of those abilities, which do not improve so dramatically as the actual levels. That is to say, a 20th level character can easily deal with threats that a 1st level character would have trouble with, but the difference in their capability levels is not as broad as the difference in their levels suggests.
To translate this into 4e terms, imagine that every character in 4e "locked in" at level 5, so that their attacks, defenses and hit points were all fixed at the levels they were at level 5. Now imagine, however, that they continued to gain new powers as they leveled up - this means that the difference between a level 5 and a level 30 character is entirely measurable in terms of what powers they have (well, and the base-attack damage bump at level 21, but I'm setting that aside for the moment). Now, this will definitely be a profound power gap - high level powers are definitely better than their lower level equivalents - but not as profound as it looks at first. The lower level powers don't exactly suck, and higher level powers might be two or three times better, but that is a much smaller multiplier than the level difference would suggest.
But now imagine that's the game you're running, and what it changes. What does it now _mean_ to have a 25th level monster? It's attack and defense bonuses, as well as hit points, should be keyed off level 5, but its damage is pretty much unchanged. It suddenly makes sense that a troop of pikemen is really dangerous, even to a high level monster, but that certain monsters (especially ones with abilities like damage resistance) are dangerous because of what they're capable of. Elites and Solos becomes the really important currency because the bump in attack and defense can be more potent than many levels of powers (and with HP capped around level 5, they will thankfully die eventually).
This is the heir to an idea that some people tried with 3.*, of capping level advancement at lower levels to keep things gritty, and I think this approach serves much the same purpose. If you lock down early, then every +1 you can squeeze out of play suddenly carries much more weight, and a lot of feats and powers suddenly look a lot more interesting.
Now, 4e doesn't need this. The way it handles NPCs allows for a lot of DM hand-wavery to just say that the town guards are whatever level they need to be, and sometimes that's all you really need. I dig that approach in a lot of games, but I admit it rubs me raw in D&D - it makes the treadmill a little bit too apparent - and something like this lets me imagine the world external to my characters as fitting together in a way that suits my sensibilities.
Anyway, I think I'm feverish, so I dunno how much sense this will make, but I'm scheduling this to post because I'm hopeful there's some nugget of utility to it.
1 - And better gear. But I am temporarily setting that aside for the moment because, frankly, the frustration that comes of tracking gear in 4e is such a profound thing for me that it probably merits its own post sometime.
2- I picked level 5 because the average bonus at this point is near 10, so it's close to the balancing point between bonuses and dice being dominant. Given the way D&D works this is mostly just sleight of hand, but it's something I instinctively gravitate towards.