Is SR4(A) more lethal at the beginning than SR3, or am i doing something wrong? Options

[Dhuul]

Hi Everyone!

I have enjoyed reading this Forum for a long time and now decided to take part actively as my group of SR3 veterans now started playing SR4A and some questions start to come up in the process of learning the game. The name of this post is also the first question i wish do ask. The situations when this question came up occurred in our first two sessions:

1) two PCs (two physads) fought three gangers (the templates from the corebook) and had quiet some trouble at first but managed to come out having taken only a few boxes of stun damage.

2) I put four PCs (a Hacker, a Street-Sam, a mage and a Face/Physad) up against four devil rats. The outcome of this was that the PCs took some boxes of stun damage in a fight that lastet 3 or 4 combat turns.

3) shortly after 2) the same group encountered a lightly altered corporate security grunt from the templates and force 6 fire spirit ordered to protect the grunt. If i had not shown mercy (or rather seen my own stupidity of throwing the spirit at the players) all the PCs would have died because the mage was knocked out cold by the spirit from the astral when he was sustaining a spell while perceiving normally (even though he knew a mage should be around as they encountered a magical barrier before). After that, i used the spirits forces to protect the other NPC (leaving the NPC-mage i had also planned for that encounter at home) and i would have killed all the PCs if i hadn't played the spirit in a way that the players were able to kill him easily then.

The thing is, that with starting characters from SR3 all those encounters would have turned out clearly in favor of the PCs, but apparently not in SR4.
The starting characters seem much weaker, not even able to defeat some devil rats. I am re-re-re-reading the rules to see if we did something wrong, but i can't find any grave mistake done concerning rolls. I realise now that a force 6 fire spirit seems to strong an opposition for starting characters, even though the PC-mage was able to conjure those quiet easily.

Even though i understand now, that starting characters should now be pitted against to heavy an opposition, yet a few devil rats should not pose a threat, should they? Are there any more traps i can fall into, beeing used to SR3? I don't want to kill my PCs because of my ignorance of some changes in game mechanics.
Is this increased lethality maintained throughout the game or does it "wear off" as the players gain karma and are able to improve on the characters?

thanks ahead for your answers,
Dhuul

PS: I am sure that this is a repost of a topic discussed often, yet i couldn't find anything related in this forum (mostly because the search told me, that my searched words were to short). I am sorry if i start my appearance in this forum by repeated an "age-old" question, but i would like to see your opinion on this topic.

PPS: I am sorry, if this post is somewhat chaotic an badly articulated. English is not my native language (i am from Germany) and i haven't written anything in English for a long time and i am only just warming up again.