UPDATE:
Here is how I had to do it to get it to work:
1) Do complete 5.0.1 restore on my 4s
2) Do 'restore from backup' from my 4 to my 4s through Itunes (this took almost 20 min as I had over 190 apps to restore)
3) Confirm all apps are reinstalled etc
3) Then jailbreak and reinstall PkBackup
4) Then used my 4 backup on dropbox and reinstall and all is great!!
Hope this helps someone!