It is true that semps do go thru color changes as the seasons come and go. To give you a better sense of how much change there is thru the seasons and thru different climates, just browsing thru the Semperivum database and choosing a semp to look at can give you a clue.
For example, Hhere's a link to a semp that you can see color changes thru the year as photographed by valleylynn and in comparison different changes due to zone differences as photographed by others in the USA (just scroll down to the photos on the bottom of that screen of info for the semp Westerlin):
Hen and Chicks (Sempervivum 'Westerlin')
