If you're living in the US, you won't get the LSD anyway, at least for the near future. And the LSD is nothing new to Porsche.
PASM is new to Porsche, indeed (the Cayenne system is different) but I don't see anything very expensive.
Maybe this helps: when I asked my insurance agent about how much the 997 Carrera S would cost me, he looked up the "category" which has been "assigned" by a insurance commission (taking in consideration repair cost after an accident) to the 997. In Germany, the cars are in different categories depending on price tag, repair cost (parts and labour), accident/theft probability and theft protection.
My 997 Carrera S has been "assigned" to category 27 for a full coverage and I can assure you that 27 is very low over here. This means that repair cost is pretty low and if you look at the new maintenance schedule (1. inspection after 30000 km, exchanging sparks after 90000 km, etc.), I'm pretty sure that the 997 costs you less money than your M3. Another point is also the fact that Porsche is pretty cautious with new electronics gimmicks, this is why they're not usually known for such problems. Best example: the chrono sport package. It took Porsche many years of development and testing to do it right and offer a system which works well without any complications. Now compare it to the M3 stuff.
The only really expensive thing is the PCCB brake. Not only does this brake cost a lot of money, a replacement disc costs a fortune and trust me, if driven hard, they don't last even close to the formerly claimed 300000 km.
If the discs are still somehow OK and can be refurbished, replacement cost is much lower.
I hope this helps a little bit.