WRT handling, the 2001 is indeed a little stiffer than previous models, which is good. I actually saw the Silver Sport Edition briefly in a NA Auto Show video clip. Very nice, and it would have the Euro-tuned suspension. If you get a regular RX, just ask your delaer to throw a set of Michelin LTX or Cross Terrain tires on it and you will get an immediate handling upgrade. Rumoour has it that one of these tires will be come standard on the 2002 instead of the pedestrian Goodyear Integritys. Also, see below in my message for a really cool wheel/tire upgrade.
In terms of "quality", this is a proven vehicle in it's third year. It keeps getting better as Lexus listens to customers and makes tweaks. The MDX, though a great design, is a question mark until enough data over time is collected.
You want mods? I'll give you mods!
For both appearenace and performance, Rod Millen Motorsports: http://www.rodmillenstore.com/rx_300/price.htm
For other sidesteps and guards:
Hope this helps,