Maybe. Download TinyUmbrella The Firmware Umbrella - TinyUmbrella select save all SHSH blobs. You can restore the firmware version TU has saved SHSH blobs.
Don't just do it. There is a procedure.... get the information first, then read up on how to use TU.
If in Mes' instructions you dont have SHSHs saved for whatever fw it is youre looking to restore to, you can use another method to grab the SHSHs for the firmware you currently are running alreasy. Go to iH8sn0w.com and get iFaith. It will save the SHSHs, create a signed custom firmware for you, then you may shift+restore with it.