In summary then, larger fans (with lower pitched blades to maintain the same
power input requirement) will produce more thrust. Seems reasonable since that's the way normal propeller driven aeroplanes seem to work.

It also seems that the fans you can actually buy are not optimised for low speed thrust. Not surprising, really, since that's not really what most people want out of a jet. It's like looking for the best race car to buy for pulling stumps.