Hi, let me relate to you my experience with Toyota (which Lexus essentially is). I've owned both the IS200 and GS300.
Years back, I got my GS300 for $245k. I also had an E46 318i at that time and no matter how hard I drove the GS300, it did not feel premium. In fact, it felt only like a more luxurious Camry despite it being rear-wheel drive with six cylinders and what not. So disappointed, I sold it after six months with a depreciation of $75k. Takers were few.
Being a petrol head, I bought the IS200 thinking maybe the younger brother was better. Well, it felt good but only relative to its japanese contemporaries. Compared again to my E46 it was a let-down. So I sold that after six months too with a depreciation proportional to the GS300's.
The cars just paled in comparison to the E28 and E30, let alone the E39 and E46. And mind you, both cars were not particularly smooth or quiet that the commercials would want you believe. My conclusion is that Toyota is at least two generations behind BMW when it comes to driving pleasure.
My advice to you is stop thinking and do it! Get rid of that BMW-wannabe. Get the real deal. An E90 beats it hands-down, legs tied and blind-folded. A F10 is what Toyota hopes to achieve three generations down the road.