Folks, thanks very much for the advice! I'll likely buy the expansion bundle, but only install DA at first and AFTER I've played a couple of games of DL. ToA will wait for a bit, I suppose.
After reading about all the changes/improvements I was already to go for it. But the reasonng that you all give for ramping up to ToA makes a lot of sense and I have to bow to your experience.
Thanks again. I truly appreciate the help!