I'm a tech at a local Saturn dealer, so I'm very famalier with the 2.2 ecotech.. I haven't seen many mechanical issues with these engines, expect for normal items that go bad on all vehicles. (timing belts, water pumps, thermostats, alternators, etc.) I've seen two engines need replaced since I've been working there. 1 was because the guy towed his 5 speed in gear and shot a rod out of the side of his block. The other is due to the idiot not changing his oil for 15+ miles between changes causing a huge amount of carbon build up on his piston rings ultimately scoring the block to hell...
That being said I'm somewhat famalier with the 3.4 and not to worried about the intake plenum. We have a guy in the shop who used to work at chevy who has done enough of these. He's got the lower plenum down to a 3 hour job and I'm sure he'll help me on a Saturday if I run into any issues. I have absolutely no eperience with the 2.4 or the transmission behind it.
Is the 2.4 a worthy engine?? Does it use the same transaxle as the 2.2? Does the trans hold up to the 2.4 like it should?? I'm guessing there is a reason Olds switched from the 2.4 to the 2.2??
EDIT: This doesn't have the 2.4L "quadrajunk" does it? If so I better stay away.
One more thing.. Saturn has the same issues as all other GM's.. Ignition switches, BCMS, window regulators, ignition cylinders, occassionally an ABS sensor or wheel bearing...None of these worry me, any other issues I need to know about?