When shopping for a DD for the wife the IS250/350 was high on the list until we realized how tight the fit was inside. Great looking and quality both inside and out but the front space was limited and the back seats more so. Our search moved on to the CTS and concluded with a 2011 G37 which is == quality to the Lexus but offered a more spacious sporty feel. Engine is nice too
In all honesty I would have a really hard time losing the $$ and switching cars. I definitely would not go back to the dealer and instead sell it privately. Research what they are selling for locally and take $1500 off that. Should go quick - the IS is a darn popular car.