[Gooserider]

You should get and examine the pump P-Q curves for each pump, maximum head pressure is more important than maximum flow all else being equal. If a pump doesn't have a P-Q curve available, I wouldn't buy it. Note also that the maximum flow will be at 0 head pressure, and the max head will have 0 flow, so you will never have both at the same time. The P-Q curve defines how much flow you should expect at a given pressure. Since a WC system has a fairly high resistance, a high head - low flow pump will give more flow in practice than a low head - high flow pump.

It also helps to translate all the measurments into the same units - ie either GPM or GPH, (or LPM / LPH for the metric folks) Head pressure is normally measured in either feet or meters of water. There is about .445 PSI per foot of water, so the 12VDC pump is approx 420 GPM at 3.2 feet, which is a very low head pressure. I forget the Danner flow exactly, but the P-Q curve is here on this site somewhere, and as I recall the Danner has a max head of around 8-10 feet, which makes it a better pump even though it has a lower 0 head volume.

FWIW, I ended up getting an Iwaki, but if I hadn't, the Danner was on my short list of candidates as possible pumps, so you could count me as another Danner vote, sort of...

Gooserider