Hello David and Jeff, how beautiful your "returners" are, my compliments indeed!
I find the sheer concept of seller's remorse very interesting: I have just a few pieces, but I don't think I'd be able to part with any of them any time soon.
First there's the 'affection' factor: the fact it is in the collection means I wanted it badly, I saved for it etc., so it may not be getting a lot of wrist time (and in fact I tend to wear always the same two or three) but it's 'dear' in all senses.
Secondly, often transactions bear indirect costs with them such as customs duties, S&H etc. and you hardly ever get to recover them in a subsequent sale.
In the end, the very thought of possible future seller's remorse seems right now enough to prevent me from selling any watches. Of course, that is until my tastes vary considerably or if I should accumulate a much larger collection in time, I reckon...

Cheers.
Fabrizio