I don't think there is such a thing as a "survival folder". Which doesn't mean one couldn't be made, but I think it'd be rather heavy and clumsy.
If you call some good folders "survival folders" you've moved the limit for what a survival knife is pretty much, so much that almost any decent knife could be called a survival knife. And then how do you distinguish the real ones?
That said, the best folders I have experience with all have limitations which makes them unsuitable from time to time. The strong ones are usually metal for example, which isn't what you want in cold weather or they can be difficult to open and close with gloves and/or cold hands or they may be too weak to stand up for inexact and forceful use which you might be expected of you in stressful situations.
My suggestion is a small, shortbladed but good fixed blade knife as the survival knife (like the WM1) and a larger folder which you think is better for day to day tasks if that's what you're more comfortable with.
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Urban Fredriksson
www.canit.se/%7Egriffon/
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"All this takes only about ten seconds, and then I hang the knife vertically, with a nail through the thong hole (and that's one of the big reasons why most every LOVELESS knife has a thong tube; it makes things easy, handling the blades and knives here in the shop)."
- How to make knives, Richard W. Barney and Robert W. Loveless