I always enjoy lying in bed and being able to hear the foghorn, but only if it is reasonably muffled, so I can drift off to sleep while it is sounding.
On QM2 we always say no upgrade, simply out of fear of a Q3. As well as no balcony, you have to have your blinds down when it gets dark, which I would hate. Having said that, years ago, I didn’t think about it, and we were upgraded - from a P1 to a Q5. Phew!
I always had the vague impression, based slightly on my own experience and on some anecdotal evidence, that Cunard liked to upgrade newish passengers to get them hooked on dearer cabins. And who can blame them?
The only problem with putting it in checked luggage is that it may not be to hand to assist you through unpacking, if the suitcases don’t all arrive together. I admit, though, at Southampton at least, the luggage does usually come very promptly.
Just out of interest, if you were to experience very poor service, as happens sometimes, if only very occasionally, how could you remove the ‘service charge’ from the all in payment? I suppose they would just give credit.