So I did Jailbreak again and restored the backup. At first sight everything was OK, except that in the car when heading home, I saw that the phone reception was bricked (baseband ?). So I had no phone for 12 hours (the time to get back to my PC which I left at work) and had to restore again.
For the time being I’m not jailbreaking and am running with the basic (Apple approved) applications.
And you know what: the phone is way snappier and I have more free memory even under heavy use (BeatMaker, …) meaning less reboots needed, which is quite rewarding.
So it’s the one (iPhone without chains) or the other (snappier more responsive iPhone), I guess…