Agreed. The 3.5 is the motor to have in the Dodge line-up. No issues with sludge in that motor at all.
Be aware though, that it is a SOHC engine, belt driven, and the belt has to be replaced every 100K miles or so. It is also an interference engine. So if the belt breaks, you'll smack a bunch of valves. But many of the manufacturers make engines with this design; Honda comes to mind, for one.
It also has the water pump inside the engine, driven by the belt.
Otherwise, it's proven to be a good, reliable, peppy engine.