One thing I haven't seen mentioned here about silk type filaments is the additives they use to create that nice finish. For most filament brands it is a combination of TPE's, polyesters, and lipids. While it makes for a really nice looking finished product, this does mean that things made from a silk type PLA filament are going to naturally be more "sticky" and flexible than ones made from a PLA filament that is made from a purer resin. It also means that the parts are going to be better at resisting wear and abrasion, so maybe the tradeoff can be worthwhile if you're able to design around these differences.