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.
Topre switches aren't stand-alone switches, as in they are mounted to the plate. This means that the overall board is much stiffer (less flex) and less likely to have a key that feels bouncy.
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.
Most of the high quality full sized mechanical keyboards have steel plate mounted switches to improve build quality and typing feel/sound. The switches on the Race 2 are mounted to the PCB, which improves modifiability, but has the tradeoff of reduced typing feel and sound.
There are not many products that propose both wireless and backlighting. Plus on the K810 backlight is handled automatically, and it's working like a charm.