I'm also a newbie and I will be purchasing this exact same watch from Davidsen very soon but I have to post and say something on this issue...
namely, we are buying contraband - even though we hear of good things from specific 'dealers', they are just that - dealers who are helpful in this respect because they are either good guys or want to keep a good reputation but ultimately, they have no real responsibilities after you receive the watch.
Would you as a seller of any goods be comfortable to send out your goods to customers on a promise of a return? I know I wouldn't and neither would (m)any stores I know of unless they know the customer beforehand or had collateral.
He is offering to replace the watch for you, I'm not sure what more you want - remember, these are not normal shops or products; they are dealers in contraband.
From a personal position, I wouldn't have gone so public about this without at least letting Davidsen remedy the problem, as he said he would. Only after that is done and failed then I would've asked for advice on the forums.
Sorry if I come across harsh or unreasonable, but that is my personal opinion.