Hey, GL with this fella. I think you could really be onto something here. Not sure what kind of market exists atm for 'artwork' fins (for lack of a better term), but it sure feels like a niche one with massive potential for growth.
Don't think Danny was being cynical, just blunt and interested.
Some thoughts going through my mind:
I've voted for no9 - clouds. Reason being is that I feel out of all of them if fulfils two criteria. One, it's highly visible for it's colours and design and so will stand out and be seen more in car parks then may-be other colourless designs. And two, in my mind it represents who I see you as a brand better. Ie. It's more consistent with your previous artwork. (of the others only 3,5 & 8 only really seem to follow your lineage, to me - maybe 8 is more so than 9 with it's 'sunface' image).
For me, the power in this kind of product is in it's desirability. It need's to be cool and fresh. Massive marketing campaigns not only devalue 'coolness' but are also costly. Therefore, I think if you are only choosing one design to produce atm it needs to have a good visual impact in the car parks. A subtle bland design that is easily overpowered by board decals or just the miserable grey/wet weather could mean a potential customer doesn't see the fin at all.
Keeping the designs so they are (or become) recognisable as yours, or even better synonymous with Droog79 will hopefully create not just a desire for 'arty fins' but for YOUR 'arty fins'. Hopefully this kind of branding can increase your production of not only fins but all other Droog79 items.
The only real possible pitfall I can see is that when a customer chooses a fin, if they are looking for a certain shape for performance then how does that effect your ability to sell to them?
Looking at SUP fins on ebay, some of them are going for <£100! Almost makes me think I should start laying up some fibreglass. The point I'm making is that bespoke fins, although more time consuming, may not be so far off retail pricing as to dismiss them altogether. I personally think that bespoke fins made by you can only add to your brand. It makes you more accessible as the artist and personalises the whole brand. Adding a certain amount of prestige to owning an original as opposed to just a 'print' of the original.
Anyway. Some food for thought, probably all BS though. Wish you the best of luck with this and hope to see some of your fins loitering around sometime soon.
PS. If this takes off, I'd love a bespoke fin of you as a collectors item. How much you selling the old ones for?