Thanks again for the additional comments. As I said, I just thought I would try it and ask for experienced suggestions, all of which I greatly appreciate.
I have a non-AF Tamron 2x that I have used some with Tamron Adaptall 80-210 zooms and it worked fine for the few shots I took, both with the K10D and the ME Super. I just viewed the digital shots on the computer though, and didn't really get into a full analysis of the quality, a task for which I am not qualified at my level of expertise. But for me just playing around in the yard shooting birds and the accompanying felines they looked fine, and I am sure I can improve on them as I gain experience.
I want more range, primarily with digital, for longer wildlife shots so I guess the best step is longer primes such as 300mm or 400mm without the teleconverters.
Thanks again. It is amazing what one can learn from the voice of experience.