Reviews of this keyboard: http://www.monoprice.c
No N-Key Rollover. The description says 64 key rollover but the reviews are stating that it's more like 6 key which is what USB usually supports. Might be important if you're expecting to press more than 6 keys simultaneously.
It doesn't matter if the branding says iOne or Monoprice. Both of these keyboards were made by the same manufacturer (iONE). One can speculate that the quality has changed within this product line over the years, but to argue that the products are different due to a pricing tiers is unsubstantiated.
People looking for a basic mechanical keyboard should keep an eye out for a the Rosewill 9000 series and the 9000 ivory. They are Costar-made, as are "top-branded" FILCO. The Rosewill USB connector problem has been fixed. Those boards have hit $55 shipped recently, which is only $15 more than this keyboard, while they're superior in quality.
EDIT: To provide more color, the Scorpius M10 was discontinued, due to reliability issues. Monoprice commissioned the excess stock to be re-branded under the Monoprice name. User experiences show that this is certainly the case. Part numbers from the Monoprice model correspond to the M10. The build/revision dates from recently purchased Monoprice units report 2010.
EDIT 2: http://imgur.com/a/bL3qR The soldering quality is harmful to the eye. An unresolved problem with the M10 which persists after the re-branding. Photos 4 and 5 depict careless and atrocious solder joints.