CodingBadly:
Thank you for the information on the WDT device independent information. Would you provide some more information on why you would suggest using TMR0 on the ATtiny85? I haven't run any of my raw WDT tests on that chip, but noticed that it does have an 8-bit timer1. Since TMR0 on the standard Arduino's showed some potential bias problems, which as we have discussed, is probably due to TMR0 being used for an interrupt to maintain micros, etc.. I assumed that would be a similar problem on your ATtiny85 core (I haven't looked at your core code in any detail).
Also, I posted this question in the Programming forum, but I had some difficulty getting my #ifdef to recognize the ATtiny85 was being compiled for... I would appreciate advice on how to address that issue.
Walt