4e rules in a 3e world?, pardon the length... Options

[ThePolo]

Sorry about the length, but I've got a bit to cover:

So, my gaming group and I usually switch off time between D&D and SR... been doing it that way since college (as a side note, it's nice and easy for me... by the time I run something it's got plenty of cannon support to go with it). As the current d20 campaign is winding down, the players are looking at me to start gearing up for some Shadowrun. We're thinking of picking up almost exactly where the last campaign left off (shortly after Survival of the Fittest, moving towards the Crash 2.0 to start dropping adventure seeds after a few months of play).

Our last campaign ended on a down note... almost a TPK deep in the heart of a Saeder-Kruup facility in Frankfurt Germany. One character was conscious and surrendered to security forces rather than be put down... The players want to pick up right there, as news of their demise makes it back to the shadow community. We use a character tree type system, with each player having access to multiple characters, so keeping the overlying story going is simple (even with a whole team missing). However, since we last played SR4 has been released, which brings me to my dilemma... can I/should I run a 2063-2065 "System Failure" based campaign using the SR4 rules?

I've read the SR4 book cover to cover, and I'm really looking forward to some of the simplifications and changes (even if my players aren't), but I'm also looking at this campaign as a chance to put the SR3 rules to bed... warts and all.

Now, as a long time player of the game (playing SR since the day the first blue book was available), I know that the rules are really secondary to the story, but there's been a lot of rule changes from 3e to 4e... more so than any of the previous editions. Some things just aren't covered any more, and some things are totally changed.

Any opinions? Is it so damn good that I should jump into it right away? Can 'old school' decking be handled under the new rules? Is there a compromise? Can I shoehorn in a few rules here and there to end up with a comfortable hybrid that will ease my players into 4e?

Hopefully I can find some opinions here... thanks in advance...

-polo