Default [Q] CWM question

Hi. I wanna ask about the CWM.
Let say i now backup the 4.1root (/stock), then i :

1) flash/update to 4.3 166 stock, can i recover it back to 4.1 if i dont want to use 4.3?

2) flash to any ROM, can i recover it back to the backup i did?

my question is simple, just if i update, can i recover it back to the old firmware or not.

thx