I'm not wild about firesquare, but I think that changing to a 1-1-1 model instead of a 1-2-1-2, will save about 30 seconds of recounting every session when somebody messes up. That's 30 more seconds of fun!
One thing about the 1-2-1-2 rule that D&D 3.5 had is that it made things with a 10-foot radius weak in the corners. For example, they had to fix the reach diagrams so that things with a 10-foot reach didn't have an area in the corner that wasn't covered. This is because otherwise, you could come along diagonally at a monster with 10-foot reach and end up adjacent to it without ever provoking an AoO.
The other weakness is that with the radius rules the way they were in 3.5, spells like antilife shell got silly. The general idea was that nothing could come within 10 feet of someone with that spell active. But, since it was a 10 foot radius centered on one of the external corners of the caster's square, it was only 5 feet wide along two sides, and one corner wasn't even covered at all.
So from a common sense perspective, some things should be a geometrically better fit to how they were envisioned in 4th edition. A small minority, sure, but some things.
One thing about the 1-2-1-2 rule that D&D 3.5 had is that it made things with a 10-foot radius weak in the corners. For example, they had to fix the reach diagrams so that things with a 10-foot reach didn't have an area in the corner that wasn't covered. This is because otherwise, you could come along diagonally at a monster with 10-foot reach and end up adjacent to it without ever provoking an AoO.
The other weakness is that with the radius rules the way they were in 3.5, spells like antilife shell got silly. The general idea was that nothing could come within 10 feet of someone with that spell active. But, since it was a 10 foot radius centered on one of the external corners of the caster's square, it was only 5 feet wide along two sides, and one corner wasn't even covered at all.
So from a common sense perspective, some things should be a geometrically better fit to how they were envisioned in 4th edition. A small minority, sure, but some things.