I used a D&R 900 before, we mixed Texas Brooklyn Heaven and the Garden on it. I have been looking at a Tascam 3500/3700 myself, Danny has a 3700 that I really liked when we used it for some of our collaborations. But since my 900 burned I needed a mixer quickly and didn't have the cash for a Tascam (the 3500 goes for more than 1000 euro here), so I settled for a D&R Dayner. It needed some work so all in all cost me only 500 and two days of soldering.
I think a Dayner might be more expensive in the US, Americans seem to appreciate them better than the Dutch. But if that Tascam is in a acceptable state and your trade is good for you, I think you'll have a very fine desk. Come to think, the guy I bought my Dayner from sold it cause he loved his 3500.
The Ramsa I don't know. When I shopped for that cheap mixer I did come across another Ramsa that I couldn't find info on, but on my search I did come across some very positive user reviews on the t820b you're looking at. You could check out the gearslutz forum, you'll find users of both the Tascam and Ramsa there (and Mackie's obviously, it is a popular mixer).