I have recently got a can of both from the UK supplier:
UN 54 35 mm - 30.5 m roll - £28.42
N74 35mm – 30.5 m roll - £41.58
So far have only used the 400 asa at 400 in Diafine 4+4. Long way to go yet - 800, 1250, 1600, Diafine, HC-110, Rodinal and some home made developers. Then on to the 100 asa (UN 54) and repeat!
So far I like the 400 asa and it does seem to handle bright midday sun well. Time will tell!
I usually get a 400ft can of Double-X for £30 as it is over 6 months old. The film industry like fresh stock and Double-X does not have a expiry date printed on it. My supplier keeps it in the fridge and if it goes to six months old rings me.