Hey, welcome to the board. The SMK 85 I rave about is not made anymore, but you may be able to find a vendor with some still in stock. The thing that makes my SMK so good is the black stemed "tactile" Alps sliders it has. The new ones have black linear switches by Cherry. Karl from DS International told me they changed the switches because customers complained about the how loud the switches are.
Now, for a mechanical keyboard suitable for quiet place, the only one I can recommend is the HHKB Pro series. It sucks because they are so expencive, but they are nice, nice keyboards and barely louder than membrane keyboards.