I preffer the DBC line with the DT reducer over DBU. DBU is an older line still good but not as good tech. The reactive reducer.... I don't know if it is the reducer that goes bad of the base, what happens is when you add the DRR to the DBU the DBU will curdle like the cream shot in a cement mixer. However just last month I pulled out some old DRR that my uncle gave me (it was about 1year old) and added it to new DBU and it shot just fine and looked great.

For the money though I would go with the DBC it is a better line in my mind and isn't near as fussy as the DBU. A very USER friendly paint line. I don't know how you are planning to use the base, but in my experience a hardener is not nessesary as long as you put a clear over it.