The problem with magnus skimmers is finding parts when things break. Conversely, that's a real plus for reef octopus as almost any part you can think of is available direct through their website.
I have the nwb-150 and I have no idea why it's so cheap. I know the pump isn't the best, but not a big deal IMO. When it breaks I'll get a water blaster and turn my modest nw model into a super reef octo.
The 2 things that are currently grabbing my attention skimmer wise, are the avast skimmer kits and also the new jabeo powered skimmers that are being offered by reef breeders. May be worth checking those out before you make up your mind