Thanks for the info. For some reason I (wrongly) assumed you'd started with 17" rims (hence 215/55 tyre comment!) and not 18" rims.
My thoughts regarding the shocks.... The standard issue factory shocks on most vehicles are usually built to a price and valved (generally) more towards making the vehicle ride nicely rather than to maximise handling. Decent aftermarket brands (eg. Koni and Bilstein come to mind) can cater for more sporting tastes (eg.with harder rebound damping) and valve the shocks to suit harder aftermarket springs. So aftermarket springs with factory shocks aren't ideal (ie. not valved to match), but IMHO the only reason they may not last as long is because they were most likely lower quality to start with- so will wear out quicker. On a number of vehicles I've simply upgraded the shocks to Koni or Bilstein and there's usually a huge improvement to the handling even with the stock spring.
