The caddy I've been looking at for my SSD-swapping plan is this:http://www.quietpc.com/nof-ssd-caddy
It takes (up to) 2 x 2.5" SSDs and allows them to be slotted into a standard 3.5" floppy-sized bay. I understand the DS1 case comes with an adapter to convert one of its three 5.25" optical bays into a 3.5" bay, so it looked like an elegant solution to me: the convenience of (occasional) drive swapping without opening the case. And then it would simultaneously free up the regular HDD cages so I can remove them to improve airflow.
... but it's a very good point about the connectors maybe not liking repeated swapping. According to Wikipedia, the SATA specification only rates the connectors for 50 attach/detach operations. (eSATA is naturally designed to be more robust and is rated for 5,000 connections, according to the same article.)
50 times isn't a lot of lifespan for the connector on an expensive SSD, but then again I'm probably kidding myself that I'll be swapping more than a few times anyway, if I'm honest about it. I don't expect to regularly use two OSes: it's more that I'm attracted to the theory and technical challenge of building myself a Hackintosh, but wanted the security blanket of an easy way to get back to Windows if I didn't like it or couldn't get it to work, lol.
I'm keen to avoid needing to use complicated boot loaders and umpteen partitions etc. But it may be that I don't need to swap the physical connections/drives anyway: I assume the new world (for me) of AHCI, UEFI, etc, still allows a choice of 'boot order' for attached disks, so I could maybe just keep two SSDs in that little caddy and simply select in the BIOS when I wanted to boot to t'other one?
On the subject of positive pressure and airflow... I can't think how I can determine for sure whether I've built something with positive or negative pressure, other than simply waiting to see where the dust gets built up.
So I'll just aim to have slightly more (dust filtered) intakes than exhausts, take the side off every few months to check and only worry about it if my case starts clogging up too often.
Would it be a good idea to budget for additional very-low-speed case fans? There are lots of options in the DS1 for extra fans, including filtered intake fan(s) at the bottom and exhaust fans underneath the 'chimney' at the top.
Adding more fans seems counter-productive for a quiet system, but I'm wondering out loud if it's generally better to have more fans running at very low rpm, or just two or three fans running at medium speed, to get the quietness I'm looking for?