I think you will find that the addition of LCD's and Buttons to the Amiga Chassis will be a personal preference.
Personally I don't see anything wrong with it, but to be honest its not my taste - for me I would modify an external 3.5" FDD chassis to accommodate either device and then modify the motherboard to see DF1 to be DF0 at the flip of a switch or key press on boot.
In regards the HxC, while it is a good little device it does have some issues with disk format and conversions. I think its a great solution to an otherwise devoid format for mass storage - especially for the CPC and MSX range of computers.
Forgive me for discussion on price points, but I have seen the HxC continually increase while the chip count and foot print decreases, Knowing what I know, I find them an expensive solution considering the same sort of money on an Amiga will get you an internal mass storage solution.
Knowing what I know, one could easily produce a HxC clone for not much more (perhaps even the same price) as the Gotek devices to the consumer and still make a tidy profit.