hat shield lines up perfectly with both my Diecimila and Duemilanove, I haven't got the old mega, but I believe shields should be compatible regardless.
I had a Duemilanove that needed a connector reworked for alignment.
but you will bash the arduino team without even contacting them first, sounds like this "reparable" reseller did just that, sold a defect board as repaired
mega2560 pin spacing
That spacing on the Eagle .brd file for the MEGA2560 is 150 mils (0.15 inch) rather than 160 mils (0.16 inch) of the other Arduino boards and shields.
Spell checker mistake should have said reputable