I've got/I have the scars to prove it

Question

A comment: X method is prone to causing trouble. I have the scars to prove it! Big pain. It's a waste of time and is just awful. The speed boost that brag about is almost completely non-existent.

B comment: If you're looking to learn something new, it's an excellent choice. I certainly enjoyed the degree of customization and speed that you can achieve w/X method.

They see the same thing from their own perspective and experiences, but A somehow thinks it's a pain in the ass to learn and B enjoyed it when he had the free time to spend on it.

I don't know the register here, informal maybe. They're talking about some methods that aren't an appropriate way for fixing PC issues. The thought is 'Efforts are always in proportion to results'. An easy method that produces poor results, which is enough for now; and something more complicated that brings good performance but the price is time. Something like a handy out-of-the-box installation versus a system with a highly-speed boost and fine-tunable control system.

How do you say "I've got/I have the scars to prove it" into Spanish?

• Tengo cicatrices de esa batalla imposible/que no quieres librar. (¿Literario?)

• Te lo digo por experiencia propia, eso es puro sufrimiento. (¿Religioso?)

• Te lo digo por experiencia propia, es para puro sufrir. (¿Coloquial?)

• Te lo digo por experiencia propia, es un dolor de cabeza. (¿Neutral?)

• Te lo digo por experiencia propia, es un dolor en el culo. (¿Vulgar?)

What's a better choice of words?

Answer 1

We may consider two requests within this question For the expresion

I've got the scars to prove it

is the equivalent to say

estas cicatrices no mienten

Of course, it could be put rather literally too, like cicatrices que atestiguan (there are many examples in the Spanish literature to convey such signs one can exhibit of undergoing intense suffering) As for your usage, I would say that it may sound a notch too elaborate or uncommon in Spanish for such an everyday communication note.

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The comment A phrase is therefore very likely subject to idiomatic and regional variations. It will depend a lot in your audience and the degree of informality you want in your text.

You are probably safe with using:

No vale la pena, [es un dolor de cabeza | un sufrimiento innecesario]

So, the (A) comment

X method is prone to causing trouble. I have the scars to prove it! Big pain. It's a waste of time and is just awful. The speed boost that brag about is almost completely non-existent.

shown with two possible versions:

• neutral
  

El método X es demasiado proclive a errores. Un dolor de cabeza. Una experiencia penosa y estéril, una verdadera pérdida de tiempo ya que la tan publicitada ganancia de velocidad es insignificante.

• more informal (a colloquial tone with a South-american —Arg, Urug— flavor)
  

El método X es una bosta. Un desperdicio de tiempo y un verdadero dolor de huevos. El supuesto aumento de velocidad, que tanto prometen, ni se nota

Answer 2

I guess you are going to get different expessions depending on the region of the answerer. Mine one is Spain (European Spanish), just for the record. I would say a good approach in Spanish to what you are trying to say is

Pelearse con algo.

Example:

Dicen que la librería X va bien para este problema, pero yo el otro día me peleé con ella y no hubo forma de hacer que funcionara.

The exact meaning of the verb pelear would be, in this case (of course, used in a figurative way):

2. intr. Contender o reñir, aunque sea sin armas o solo de palabra. U. t. c. prnl.

If the subject of the sentence is not something you can fight against, another way of adapting the expression would be this:

Librar esa batalla.

Example:

El método X para resolver esto da muchos problemas. Créeme, yo ya he librado esa batalla y no quiero volver a pasar por ahí. Ni siquiera ofrece el aumento de rendimiento que promete.

The DLE states that librar can also be used in a figurative way in the meaning we are referring to:

4. tr. Realizar una batalla. U. t. en sent. fig.