I managed to get the bluetooth file transfer working between my PC and K750i. Below as a picture I took yesterday of my 360 for a comparison against The Picture I Took in Currys of their broken 360.
So as you can see the image is much bigger. Looking at the number of pixels on my new phone against my old, the new one has 95% more pixels.
I took the same picture with my two mega-pixel digital camera and both images look surprisingly similar. I would have posted that too as a comparison, but where as the image from my new phone is 233KB, the one from my camera is 1.13MB. To post that here I would have to compress the image and that would make it an unfair comparison.
The cut-up mouse pads under my 360 are there as vibration/sound dampening to stop it rattling the stuff on my desk (it's near whisper quiet now).
Anyway I have been transferring files back and forth for a good part of the day. And transfer is slow over bluetooth. I worked it out based on knowing how big a file was and how long it took to transfer that the transfer rate over bluetooth is 9.71KB/s which is ok, but when transferring a 10MB MP3 file takes nearly 20 minuets. I might try the USB data cable that came with it. And that's odd, normally you have to buy the data cable separately for mobiles which is why I bought a bluetooth adaptor for my PC in the first place, but with this phone the data cable came in the box.