HW100 is a great gun but much more expensive than the 400, even second hand. I've seen HW100's on HFT and FT shooting lines, but shoot the 400 myself at the moment. I doubt there is a better value for money gun than the 400. I have a classic because you get more shots per fill than with the carbine.
EV2 mk2 with 2009 big Nikko
HW97K with 6-24 Nikko Nighteater