I'm glad to see someone understands what I'm babbling about!
I'm not too concerned about the flow sitting at the bottom, because that's where most of the heat appears to be, plus the top is polycarb, so there really wouldn't be much benefit in trying to equalize the flow within a channel.
I think that part of the problem is/was this:
a) the simulation didn't have a nozzle plug, it had a huge 5/8" opening. With a nozzle, the flow should strike the baseplate, then exit smoothly (more or less).
b) the outlet had a swirl going on, which may have had a certain effect: that's been fixed (curved outside wall is now square, and the outlets within the top have been made larger).
As for adding deflectors, I wouldn't do that near the jet: I want to leave that one alone so it can "be all that it can be"
I'm gonna send this to Roscal, for analysis round 2, but first I have to make sure that the nozzle will allow my pump to work within an effective range.