Don't believe the IMS issue is sorted for a second: It's not! The later revisions by Porsche were better, but could still easily fail. Any IMS engine is a risk, which is why I suggest getting a really leggy 100k+ one as if it hasn't gone by now, then it's very unlikely to.
It's the same engine in the 3.4 as it is in the 3.6, however the bores are bigger so the walls thinner so you can guess how much more likely scoring is to occur Again though, as long as you get an inspection and don't expect to put a billion miles on it in a year then it's just another check you'd add into the service, and keep an eye on it. If the car is showing no scoring at all, then it's likely to be good for years to come. If it's showing a bit then you have haggle room, if it's awful then walk away or pick it up for peanuts and take it to Hartech.