In terms of digital why would you need a wl finder with live view on the back screen?
When I have the camera (film or digital) attached to a telescope or a long lens that is aimed at an object that is directly overhead, it is very difficult to get my eye to the back of the camera to be in the proper position for viewing through the eyepiece or for viewing the LCD. Being able to view through a waist-level viewfinder on the top of the camera is a nice option.
Plus, the Live View feature on my digital SLR is too difficult to activate and automatically turns off after about 30 seconds.

Nikon mirror lens by Narsuitus, on Flickr