First of all welcome to the forum!
The Schallochs do have a good reputation, solid construction and more lugs than necessary
(Just joking, of course you can tune a conga more precisely with 7 or more lugs.)
Having that said, they are nowadays mass produced and they also have a low-grade series.
But the 400 + 600 product lines you mention seem to be more than OK.
As long as you do not mean this line:
viewtopic.php?f=14&t=2857&hilit=schalloch+thomas Cf. the first picture
