This is my personal opinion: I have had the SD43 soon after it was released (with the MK1 dial ha ha) that was a few years ago. It got moved on for the reason my watches get moved on - I wanted to try something else and I wasn't wearing the SD43 so much. I have a 6 3/4" flat wrist (5' 10" and 160pounds if you really must know).
The SD43 wore fine as I go on lug-lug size not diameter and anything under 50mm is fine for me. With a flat wrist I found it wore ok - if you have a round wrist (more flesh I guess) you may find it slips around bit but it does have the easy-link clasp for a good fit. Anyway it's sold now
I also have a Submariner ND 41mm which is still in my little collection. I think this 124060 iteration bought it back to classic proportions shaving off a millimetre here at the shoulders and adding back one there at the bracelet balanced it out after the more boxy 114060. It is classic dive watch.
Here is the 41mm compared to my Hulk and YM40
This was the 114060 by comparison (yes I had one of those too!)
Sadly the SD43 has become just another jewellery watch - now available in bi-metal
- but this is probably inevitable.
One Rolex I wish I still had was the SD 16660 sold on this very forum - if anyone has it please PM and I will give the going rate. It had the silver surrounds on the dial but it was such a beauty and with provenance of the sale listing in a famous auction house with reciept, here it is:
It was bullet proof and yet vintage with a tried and tested rock hard movement and case that would protect it to 1220m and beyond.. what's not to like..
Anyway OP - I would get the one you like - not quite sure of the stipulation for an 'unworn' watch as long as its under warranty you should not have any issues? A couple of marks on the clasp / polished case can be fixed at next service? Seems like you are keen not lose money - there is a reason the SD43 is more available. . .
Here is a left field suggestion - what about a YM - can be bought below list with some hunting and is a rather elegant alternative
Good luck with the hunt.