Wow, that's definitely… something!
You definitely don't want to install a stock C7 in an SFF build… ?
What about the widely used custom mod with a Noctua fan?
Would that help? Would it even be worth the hassle, compared to stock NH-L9i or Black Ridge?
Changing fan doesn't really help because it's the issue of fan blades being close to perforation and causing turbulence. Actually IMO C7's fan is less audible on it's own than noctua's 14mm fan because it has pretty unique frame, so changing it doesn't really make sense.
If you have a thicker case, higher clearance for the CPU cooler, I would actually recommend the CU variant because it is really quiet.
I'd recommend going with NH-L9a for AM4, my NH-L9i behaves neatly and doesn't irritate because there's enough space from perforation. Black Ridge also behaves similarly, although it requires specific board to fit (AORUS B450/X570 only AfaiK) and even with that specific board it won't let you mount 2.5" drives, aand still you can't use the 120 mm fan with standard memory (VLP are pretty uncommon/expensive), aaand on top of that there are issues with the brackets if you get the AM3/AM4 combo bracket variant.
If you want to have absolutely quiet system, but you may compromise on the temperatures, there are four mounting holes hidden within the cover perforation above the motherboard for 120 mm slim fan. You can use a radiator like NH-L9i/a or something from Dynatron and put a slim fan pushing the air out through the perforation (otherwise you'll get the same effect with fan blades causing noise). Caveat of this is the screws being in perforation as well, so it's not perfect. Anyway those screw points are slightly off from the perforation layout, so those should be visible. You need to use standard profile ram for those to fit, with VLP memory and low radiator you might fit a 25mm thick fan.
Another question about your shipment policy.
Are you shipping by nation? That's how I would manage the shipments.
If that's the case, do you have an order you plan to stick to? And, if so, is it possible to post it here and, maybe, update it when the shipment is processed? I can't wait to toy around with the Sentry, any info on the status of shipment you can share would be totally appreciated. ?
We went with export packages first (export as in outside EU) as the shipping would be longer, and we didn't really know how much time would it take this time around because of black friday and xmas etc. We're not shipping by contribution ID because this would be waste of time to keep track of.
Orders from the North America are over half of all orders including the ones in the EU, so effectively those are dominating the first shipment focused on export packages.