Anyone gone from 535d to 335i

[Ultraviolet]

All

I'm thinking of changing the 535d m-sport touring for 335i m-sport touring(must be an auto, the wife won't drive a manual). Anyone does this? If so, did you regret it? what should I look out for?

Also, any ideas on cost to change from a 535d m-sport touring, silver grey, pro nav, leather, 25k miles, 05 plate to a 335i m-sport touring, automatic, blue/grey or black, leather, xenons, pro nav, 10-15k miles, 07 plate?

Finally, what sort of finance options should I look at (must be through BMW)?
More per month and a smaller balloon? or is there a better alternative (for a private buyer)?

Any help greatly appreciated...

UV