The N4s are really sweet, strangely only 4ga inputs. I think with the 3000.1 he is looking at though, he will get more power overall, even if it is overrated, he will still see more wattage.
Yes the Zues series has taken over the HFI series. I had a HFI2500.1D and it was good but did nothing near rated power.If youare strongly looking into getting a hifonics amp look into getting the Brutus series they are way better