Well, you boys definitely know your stuff.
I've got a FS-DE motor in mine, only done 32k miles though!
Yes, I've heard the Auto Xmsn is the weak point on the 626. Both the C4DE and its predecessor are prone to overheating (was changed to C4DE to fix this problem - but just as bad).
Luckily the old boy who owned my car previously, had an external Xmsn Cooler fitted. Regular Xmsn fluid change should prevent damage anyway.
Mazda released technical service bulletins (0400502, 01598, 003/97k, 006/95) to address these issues.
Still a fricken good motor!