Specs are quantitative aspects of the option such as the price
Pros
Pro
Compact and portable footprint
If you love your keyboard enough to want to use it everywhere, it should be portable, especially if it's as expensive as this one is. The FC660C is very compact and easy to carry around.
This board's keys don't feel bouncy thanks to it's topre switch design. Since the torpe switches are mounted directly on the plate, the board feels much stiffer overall.
Topre switches are a high end switch which typically cost a hefty premium. They have mechanical components protected underneath a rubber dome which makes them more durable.
Non standard key sizes means your aftermarket keycap options are limited to non-modifiers. This issue also exists with virtually every other keyboard that utilises the Topre switch.