We have to acknowledge, I think, that construction on this DS is not really at a slow pace at all.
Just look at it, it's got it's big gun already in place, the central core, the trenches are complete, it's skeletal outer shape is there, and that in what, 2-2.5 years?
That seems rather fast in my book. I doubt they take a back-burner for the next 20 years.
Also remember, they're churning out all that hardware we see in the OT as well during construction of this DS.
And, just to toss in an idea, who says this isn't the Death Star of ROTJ instead of the one in ANH?
We all asume this is the first, but...is it?
[EDIT]On second thought, there's too much complete on those upper and lower halves that were not there in the ROTJ DS, so probably this is the first from ANH.
Still, would've steered the discussion in a whole new direction...