UngeheuerLich
Legend
Decreased hit chance of the monster is compensated by increased damage post MM3. I made a fast calculation in a different thread (or this one some weeks ago), and you see, that a MM3 monster of 3 levels lower in high epic does about the same damage as a pre MM3 monster, but with less hits. (note, that less frequent but more powerful hits has two added benefits: 1. Damage reduction is more easily overcome. 2. Status effects like stuns don´t hit players as often.)Decreasing monster level does compensate for decreased hit chance on the part of players, but at the cost of decreased hit chance on the part of monsters. If you're 22nd level with an AC 42 defender, the monsters are already looking for ~15 to hit without decreasing their chance further.
Much like it's not so simple to compare play experience using pre-MM3 damage values, or with clerics that could astral seal for 40 hp healed, or various anti-damage techniques that actually completely negated monster damage.
So the encounter range defined in the spoiler tag i responded to, was shifted 3 levels down, and the viable range of monsters is as big as with the expertise fit.
MM3 damage and exprtise should neatly expand the range upwards, as hitting more than expected makes the experience rather better than worse and the range of viable monsters is increased.