DCF clothing can be a very niche and specialized type of clothing. Unvented DCF clothing is the most specialized and is really only the type of thing that an ultra runner would put in their vest to stay warm while waiting out a storm or something folks would use as vapor barrier clothing in a winter sleep system. There are certainly more uses, but most active use cases should be avoided in unvented DCF clothing. Vented DCF clothing like the DCF MegaZip is less specialized, but still quite niche. It is not recommended that anyone wear packs over top of DCF, do to abrasion and breathability limitations, so this restricts the DCF MegaZip to hiking, cycling, running, etc activities and mostly rules out its usage in backpacking cases. The Silpoly MegaZip is a better choice for backpacking, as it can handle abrasion. However, for almost all backpacking use cases, an improved poncho is the absolute ideal scenario where an impermeable barrier is suspended above your body, covering everything, with big mechanical vents. Ponchos, historically, are built in a very basic format that leave arms exposed, sides open, and hoods baggy. An improved poncho has sleeves, adjustable side vents, and an adjustable hood.
Shrinkage –
DCF does have a tendency to shrink. Not always, but often enough to be a major consideration. There is a theory that suggests heat is the catalyst for this shrinkage when the fabric is not under tension. This seems accurate, as I often see it after shipping or with items stored in a pack that might see high heat while sitting in the sun.
DCF from the factory has very little stretch in any direction. Items that have shrank seem to gain a stretch in the dimension that shrank. I assume this is due to the laminate mylar film shrinking and releasing tension from the Dyneema fibers. You can pull that stretch back out, very close to it’s original dimension, without compromising the fabric. However, I have to imagine that, if repeated multiple times, this would result in holes in the film. Therefore, it always makes a lot of sense to intentionally oversize any DCF clothing. It should, not only, be large enough for you to move through your full range of motion without placing tension on the fabric, but also have a little more on top of this to account for shrinkage. DCF should never be sized such that it is tight against your body in any spot. Given how little stretch it has, this is likely to be very uncomfortable, among other things. Loose and baggy is what you want.
Abrasion –
For all its strengths, DCF is sometimes not the best option for use cases that involve abrasion. The mylar laminate that coats the Dyneema fibers can break down under abrasion. The fibers remain intact and the fabric will remain structurally sound in most cases. However, it will lose its waterproof nature when the holes open between fibers. If this happens to a DCF garment, and the abrasion area is not too large, one can apply a coat of silicone to seal the area back up. However, it still holds true that DCF is not a great option for high abrasion cases. I wouldn’t recommend it for long hours under backpack straps, or for cycling pants that will rub on a saddle hundreds of thousands of times. I think silpoly or silnylon would be a much better option in both cases. I’ve had an emergency DCF pullover that lived in a running pack and would come out for the occasional rain. This item is still fully waterproof after 5 years of this type of use. However, I’ve had a DCF MegaZip that saw regular use running and cycling, but likely more importantly, lived in a cycling frame bag for most of its time not in actual use. This garment lost it’s waterproofness in a few areas where it likely abraded the mylar away while jostling around in the frame bag. This is an assumption though, as this garment has also seen some pretty hard use while packrafting along with regular use running and cycling. I might recommend DCF as a MegaZip poncho for backpacking / thru hiking that won’t be subject to abrasion under pack straps. This would likely get rolled up and stored in a backpack pocket when not in use where it won’t be bouncing around a lot. Something like that might last for many years of this type of use with warmth and weight benefits. However, I would steer anyone away from using DCF as a primary rainwear garment to be worn under a backpack. This will result in pretty quick degradation and loss of waterproofing in those areas. It appears that abrasion during storage are also a concern for cyclists and runners. For cyclists, it might be better to store a DCF item in a back pocket instead of a bag on the bike that will really jostle it against other things. For runners, it might be totally fine while stored in a running pack as long as it isn’t rubbing against other items. I might recommend that it be stored in its own pocket. Of course, you’d want to make sure you can wear it over top of said running pack, not under.
Anyone considering DCF clothing should also really consider their use case. If long term durability is a concern, and abrasion is likely to be a factor, siliconized woven fabrics are a much better choice for minimal weight gain.