Yep, life moves, on priorities change, did I like the 640d yes of course, would I have one again, possibly, but for now the Seat does what I need it to and doesn't feel like a small mortgage sat on the drive doing next to nothing other than depreciating like a lead balloon.
The usual customer annoyance on super saloons; range.
That is probably a big part of it to be fair. Visiting the fuel court every 300 miles instead of 600 gets old quickly when all your doing is commuting to work.
Of course, the one day a week when you get to open it up, the M5 nails it. The 6 other days, with all the same toys, the 530d is realistically no worse, and keeps you away from the Shell station a bit longer.