OK, I can't tell you what the C180K is like to live with but I can give you some input on some of your points / questions based on my experience with my C220CDI Elegance Auto.

Bluetooth I use it with a Nokia 6300 and it works great, with excellent sound quallity and clarity. The only pain is that you have to transfer each contact's details individually (i.e. the standard Bluetooth doesn't "read" your phone's memory) so if you have lots of contacts that change frequently then consider the phone pre-wire option with the SAP Bluetooth Cradle.

COMAND I didn't spec it on my car as I'm happy to use my Garmin GPSR and wasn't bothered about the music library. However, it is a very neat option and when it comes time to sell the car, many buyers will look specifically for one with COMAND. As far as iPod integration goes, Mercedes do an iPod integration kit which will allow you to control the iPod from the steering wheel controls and display track info on the instrument cluster. Some time this year they will be introducing a Universal Media Interface (UMI) either as standard or an option (it's not clear which) that will offer even more functionality.

Trim Line / Options Like you, I wasn't that enamoured with the Sport trim and as my wife has an R56 MINI Cooper S I couldn't see the point of buying a C-Class Sport for it's more "sporty" driving experience. I spec'd up an SE with the sort of options I wanted and frankly it made no sense financially to have that rather than the Elegance which gives you Artico upholstery, rain-sensing wipers and auto-dimming mirrors as standard. Options I took were metallic paint and auto-box (both pretty much essential if you want best return come trade-in time, and the auto-box gives you cruise and speedtronic) and I also added heated front seats and the split-fold rear seat. The heated seats are really nice in the winter and I'd consider them a necessity with Artico or Leather upholstery. Don't bother speccing the cupholder - it's about £20 from the parts dept, can be fitted in about 15 secs, and you may decide to keep the roller-door storage compartment "as is" once you've used it. Parktronic is a nice option if you frequently have to park in tight spaces (I don't so didn't have it) but you must keep the sensors clean to keep it working properly. COMAND is nice but also expensive, and it will be worth approx £1,000 come trade-in time. Another option I took which I advise you to consider is Parameter Steering which improves the steering feel quite dramatically at speed while giving you super-light steering at parking speeds.

Engine Both the C180K and the C200K are refined and reasonably quiet, but I suspect that you won't be happy with the C180K's performance after your 320D BMW. The C200K is much quicker for not much of a penalty in fuel consumption and I would say should be a better bet. I respect your comments about hating the diesel clatter, but as you do a fair mileage you really ought to try out the C220CDI for yourself to see if it is the problem you think it will be. My experience is that it's noisier than the petrol engine when pulling away or if using the upper reaches of the rev-range, but once you're rolling the engine as a whole, let alone any diesel clatter, is essentially inaudible. The mid-range acceleration performance is superb (400Nm of torque!) and quite addictive, and the engine charcteristics and the 5-speed autobox are well matched. The C200CDI makes no real sense in the UK (other than a slightly lower initial purchase price) as it gives much less performance than the 220 for only a miniscule improvement in economy.

My Likes: excellent ride quality well suited to the UK's potholed roads; you can drive it much harder than you'd think; high level of refinement; no sqeaks or rattles; (mostly) seamless gearchanges from the 5-speed auto-box; comfy seats that give no aches or pains after driving all day; simple, easy-to-use control layout; superb climate control / ventilation

My Dislikes: None, really. There are couple of things that could be better though - more lateral support from the front seats; sound from the Audio 20 system is adequate rather than excellent; large door mirrors can cause sideways blindspots under some circumstances

Overall, I'm very happy with the car (as you can probably tell!). Driving it is a fantastically relaxing experience and I find that my stress levels diminish several notches when I get in it and shut the door. One thing you need to be aware of though is that it's a very different driving experience to a 3-Series. See if you can get an extended test drive from a cooperative dealer to help you make up your mind, and do consider the diesel especially if you rack up more than, say, 15k miles a year.