I don't know which one you are looking at (stainless steel, 2-toned, or all gold) but I will share with my experience shopping used v new and what I learned.
I was going to buy an older version of the Panthere watch and was aggressively talked out of it by 2 jewelers who sat there and basically tag teamed me (totally against their interest obviously). They were super sweet and knew that this watch purchase was a big deal for me and they felt that my money would be better spent on something else. I ended up going for a different watch altogether for different reasons but I think that some of the arguments they made would be relelvent to your current decision whether or not to buy a used Panthere. These are the reasons the sales people gave me for NOT buying the used Panthere:
1. If you are getting a version with gold, the gold links on the older models are hollow. The gold itself is sold gold, but the inside of the link is hollow. The new watches have solid links. There is no hole in the middle. However, I don't know if there is actually less gold or not because if you look at the way the new watch gold links are shaped, they have concave bits in the middle. To me it's just putting the hole on the outside rather than hiding it on the inside. This honestly made no difference to me but I wanted to pass on the info in case it matters to you.
2. Also, a Cartier SA said that in the older models, the hollow links stretch a little over time, especially in the all-gold versions, leaving slight gaps between the links. I don't know that I've noticed it on actual watches tbh so I don't think that would be an issue for me personally, but that's what they all said so, again, I wanted to pass it along.
3. The versions with stainless steel are likely to be brushed stainless whereas the new ones are polished. This makes the older ones look darker. You can see in the picture below the difference between the darker gray brushed stainless vs the lighter sliver polished stainless. This is a matter of personal preference of course, but for me that was the deal breaker.
4. The new closing clasp is different and supposedly more secure and stronger, although tbh I prefer the appearance of the old version better. The older clasp has integrated links and the new one has a clear demarcation. The pics below are of the backs of watches to show this. The older links do have a bit of gapping at the clasp point, but I still prefer the appearance of it to the new version. Again, personal preference and you may prefer cleaner look of the new models.
5. Their main argument is that these are quartz watch movements which do ultimately need to be replaced at some point and the old ones are at least 20 years old already since they were discontinued in the early '00s. Depending on whether the used one you are looking at is from the 80s, 90s, or 00s, you are at least two decades closer to needing to replace the internal movement. You may never need to replace it, as I have quartz watches from the 70s from various brands that work just fine. One of the ladies said that she used to be a Cartier SA and she saw watches needing movement replacement fairly frequently before they reissued them a few years ago (when presumably people just buy new ones rather than repair old ones).
Take this info for what it's worth. The 2 jewelry store ladies were not motivated by money, as they do not get paid commissions. They were actually trying to talk me into buying a less expensive automatic movement watch because it was a better fit for what I was looking for. In other words, I felt their information was honest and unbiased.
The current Cartier SA who is paid commissions, would of course prefer that I bought a new watch through him rather than a used one elsewhere, so his info is perhaps less biased, however I have heard the same info he gave me about the links from multiple sources.
I don't know if any of these arguments are relevant for you and your buying decision, but I wanted to share what I learned just in case it helps.
Best of luck no matter what you do!
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