1) Dropped JTAG pins for debugging the '430, as I've never used them.
2) Added a 74HC4053 to the bottom face for glitching.
3) The '4053 is optional, only for BadFET use.
4) Added a high-frequency crystal to XT2, also optional.
5) Retained LF crystal on XT1. De facto mandatory, but not for long.