General consensus is that 1.5 sucked and 2.x was a lot better but still had a couple of minor issues.

Right, exactly. Most of the complaints leveled at Xing were for the older version which didn't have the high-frequency mode and which was too harsh about its high frequency filter.

For what it's worth, there's a good reason that encoders filter the highest frequencies. Because it's better to gently filter the highest inaudible frequencies and spend the encoding bits where they can do the most good.

Only when you're throwing lots of bitrate at a file can you expect to properly get away with trying to encode the highest frequencies, too.