For a removable expansion module, would you recommend a edgeboard connector or a mezzanine board-to-board connector? I'm interested in durability and assembly cost. I came across these edgeboard connectors Are there drawbacks I should know about?

I want to design a PCB for a clock using Arduino Mega, DS1307 RTC module and 1.54” e-ink display module(monochrome). The main board will contain the Arduino Mega, DS13007 RTC module and battery. A small front-panel board will hold the E-ink display. My current prototype does not have any push button but I need to add some of course. I'd like the front-panel board to be removable.

Here is a picture of my current prototype.

 

i would consider making buttons separate, for that i would use 2-pin JST connector - small and cheap.
board can have few buttons and resistors, forming multi-level voltage divider, that is easily read by ADC.

for display i would run cable directly to Arduino. or... put everything on a single shield.