What is the main advantage of Survivalist?

It can use any weapon of any perk (except some grenades), so it can adapt to what the team needs, from trash clearing to large Zeds.

What is its biggest downside?

Its bonuses for borrowed weapons are smaller than a dedicated perk's, so damage is lower, for example against bosses. Also, many players play it selfishly, which gave the perk a bad name.

The author lists more drawbacks than advantages, but says that any class in skilled hands is a strong weapon and good team support.

Perks & Classes

KF2 Survivalist: Pros and Cons of the Jack-of-All-Trades Perk

This translation of a Russian-language perk review looks at the Survivalist, the "a bit of everything from every class" perk of Killing Floor 2. The author weighs what it does well, where it falls short and why it has a mixed reputation.

Survivalist perk The Survivalist, a mix of all the other perks.

Advantages

Any weapon. Survivalists can use any weapon of any type (except some grenades), so they can deal with any group of Zeds, such as Sirens, Husks and other special enemies.
Mixed perks. Being able to use abilities associated with many perks gives a good chance of surviving to the end of a wave.
Versatility. A Survivalist can take on the role of any perk the team needs, though not as effectively as a dedicated perk.

Disadvantages

Smaller weapon bonuses. For example, Survivalist explosives have no resistance to Siren screams. The weapon bonus is somewhat lower than that of specialist perks such as Sharpshooter or Commando.
Weaker grenades. Bombs and grenades from other perks are less effective than on their own perks, so do not expect full effect.
Lone wolves. Many players take Survivalist and play alone, quickly switching style without helping the team. The author strongly advises against that, because it is exactly why the perk earned its "bad reputation".
Weak against bosses. The DPS of borrowed weapons is low because there are no dedicated perk skills to boost them.

Survivalist skill and weapon discussion A community quote attached to the guide.

Verdict

There are more minuses than pluses, but every class follows the rule of "skilled hands": in an experienced player's hands any class becomes a formidable weapon and a good support for the team.

The author describes Survivalist as "a stopper in every barrel", a perk whose character the player builds. It is a set of all the other classes: want to be a healing demolitionist? Easily. Want to burn everything around while slicing Zeds into thin pieces? Go ahead. The Survivalist's class weapons are the weapons of every other class.

For concrete builds see Survivalist guide: skills, weapons and builds.

FAQ

What is the main advantage of Survivalist?: It can use any weapon of any perk (except some grenades), so it can adapt to what the team needs, from trash clearing to large Zeds.
What is its biggest downside?: Its bonuses for borrowed weapons are smaller than a dedicated perk's, so damage is lower, for example against bosses. Also, many players play it selfishly, which gave the perk a bad name.
Is Survivalist bad?: The author lists more drawbacks than advantages, but says that any class in skilled hands is a strong weapon and good team support.