No! No! and No! I just spend the last two minths doing what you were planning to do. After all the side by side comparisons etc. My conclusion is that the New Sharp 1080p Aquos LCD is a much much better buy. Sure the Sony's picture quality might be a touch better, may be even the best in the market, right now. But, at THAT price!!!
You might want to consider the Sony KDL-46V2500 TV. This is a step down from the XBR. It has the Bravia processing engine rather than the Bravia Pro. Also, it does not have DRC 2.5. I am taking delivery on this model on 11/22.
I cancelled my order for the 46V2500 and ordered the 46" XBR3. The V2500 is a good choice but I felt the XBR3 was a better choice.
The size depends on your viewing distance. There are many viewing distance calculators available. It comes down to your personal preference. Some people like to sit in the front row at the theater and some prefer the middle or back rows.
I am 8 - 10' away. I can go with either the 40" or the 46". I feel the 46" will be a better viewing experience in HD for me.