Playing the Berlin Defence in Ruy Lopez or the Latvian Gambit with a rating of 1400 to 1800 makes no difference.
Only a good opening doesnt make you a good chess player...
This is fundamentally wrong.
Playing the Latvian you will likely win against players which are tactically blind, and lose against strong players, which will not oblige to fall into your cheap tricks. The very same applies to the Berlin, although winning against a weak player will likely be more difficult, as there are no cheap tricks.
But! trying to revive the Latvian against strong opposition is an impossible task- while reviving "your" Berlin is surprisingly easy: you just have to understand what-the-heck you are playing, and what your strategical aims are. You could even use the Berlin against very strong opposition, with very good results, although playing this kind of opening with Carlsen, Karjakin or Aronian accuracy is highly unlikely to happen-ever.
And- of course the statement "Only a good opening doesnt make you a good chess player..." is 100% right. But picking a good opening (like the Berlin) instead of a crap opening (like the Englund, or the Latvian) is a very good start.

I dont play the Grobs attack actually (ive tried it a few times with poor results), but i play any other kinds of unsound openings, like the Latvian, the Englund or the BDG.
Iam tired of self-defending me, why i play these crap.
Is a chess opening such a dogmatic thing, that only allows to play high-fashioned standard openings.
On amateur level, as 99% of us play, you can play nearly every opening, if you know the concepts and tactics.
Playing the Berlin Defence in Ruy Lopez or the Latvian Gambit with a rating of 1400 to 1800 makes no difference.
Only a good opening doesnt make you a good chess player...