Anyone familiar with the Seimens switch? I'm trying to figure out the best way to do this. Proprietary cordless or regular 2 line cordless and two analog ports.

I work on a Hicom 300, and use both Proprietry DECT cordless and and analogue 2-wire cordless. It depends on what you want to achieve.
The Siemens Dect phones we have are used in an area that require greater coverage than two wire Dect phones can provide and also provide Hicom features not available on analogue extensions like display of calling number.