SLW: New member and just read your input about RX350 engine "knocking/rattle". I share your concern. Anything that knocks, rattles, cliks, squeeks, grinds, thumps or rubs could be a potential problem and should be investigated and/or repaired. The knocking occurs on my '08 RX350 15000mi when cold and is particularly noticed on acceleration. It seems to go away when the engine warms up. This leads me to think along the lines of an exhaust manifold leak perhaps. Anyone else experienceing this problem found a fix. Living with it is not the answer.
