It's generally believed that once you've found a brand you like it's best to stick with that brand - especially true if switching from foil to rotary. Reason being that your face will 'adapt' to the type of shaver and you'll not get such good results if you switch (though this effect will decrease over time).
I've never wet shaved (don't trust myself), but I know that it's unlikely you'll ever find an electric that's as good as a proper wet shave. Neck area is particularly problematic - none of my phillips shavers have ever done particularly well there.
As for sonic, well, I thought that was just toothbrushes. What do I know eh?
Returning non-faulty goods will be at the shop's discretion. I suspect a lot of places will refuse solely on health and safety grounds.