I went from an IS200 Sport that I bought new in April 2005, to and IS250 SEL in June last year. When I handed over the keys to my beloved IS200, I felt quite sad. However, I have no regrets what so ever - I really love the IS250. It's smooth as silk, more powerful, and loads of toys and gadgets to play with. Interesting what you said about the IS200 being 'rugged' - I know exactly what you mean. IS250 seems to be a much larger car, but it is definitely less roomy in the back. However, I didn't buy it for that reason, so I have no regrets in changing. When I was looking around at cars, I considered Audi, BMW, Mercedes and even VW, but the way the Lexus Dealerships have looked after me since April 2005 counted for alot and I was never really serious about getting a different make.
Only worry I have now is about DAB radio, but guess that's still a few years off!!