Should I Play The Najdorf Sicilian as black as a 1475?

I have learned the opening theory, but I am not sure whether or not I should play it in my rated games.

You've learned all the theory of the Najdorf?

I'm impressed.

I play the Hippo. I think I know all the theory for that -- because there's very little theory.

It's hard for me to believe the Hippo is better than the Najdorf, but I like it. And given the fact that I don't play a lot of masters, I seem to get away with it.

Which is my point: I'm not a master. But neither are most of my opponents.

The Hippo may not be great -- but I know it better than most of my opponents. And so it seems to do just fine.

Would that advantage be different if it were the Najdorf that I knew well -- which might be an even better opening than the Hippo?

I'm not saying yea or nay in answer to your question -- I'm just pointing out that having a lower rating ALSO means that your opponents are likely often to be lower rated players, too. And so they would seem unlikely to know the Najdorf well.

It will be interesting to follow your progress here, whatever you decide. Good luck.

"Should I Play The Najdorf Sicilian as black as a 1475?"

• No, you can, but be prepared to lose horribly.

"I have learned the opening theory"

• No, you have not. Here is an example with like 20 moves of theory:
  https://www.chessgames.com/perl/chessgame?gid=1993385

I Play Sicilian only. Can’t even tell you what the najdorf is on the other hand.

You can’t remember 100 different lines to deepen your prep one move more than your opponent. Plus the names are meaningless.

So I would play couple games, analyze them. Maybe 2 games.
After that select a puzzle theme and check them out. You can see allot of resulting positions ALL AT ONCE. Compare them to what u played before with black and make your decision.

Should you jump off a bridge if we tell you to?

Here's something you ought to know about the Sicilian: it's not an opening, it's a large family of openings that result from 1. e4 c5. The Najdorf itself is a major branch of this family, with many, many sizable variations. The Najdorf is also closely related to the Dragon, to the extent that there exists a hybrid Dragondorf variation.

Learning to play the Najdorf against all the possible responses will take time, and it will take even more time to master them. So it will pay dividends in the long run, but you will probably benefit more in the short term from choosing a simpler opening (at the expense of choosing an opening that opponents at your level probably know well).

An anecdote (which may or may not be true!) is that Najdorf himself was asked late in his career why he'd stopped playing the Najdorf, the opening he developed. He responded that (to paraphrase) there are so many lines to the Najdorf that every time he plays it against some well prepared youngster, they destroy him with a variation he's never come across before!

"An anecdote"

• Here Fischer destroyed the Najdorf of Najdorf
  https://www.chessgames.com/perl/chessgame?gid=1008414
  Here Najdorf did not dare to play the Najdorf
  https://www.chessgames.com/perl/chessgame?gid=1044016
  https://www.chessgames.com/perl/chessgame?gid=1044320

Actually I'm of opinion that you can play any opening regardless of rating.

For example a 1475 is unlikely to know all the theory of the Najdorf but that equally applies to their opponents if they're playing people of a similar strength. As long as you know the general ideas, what you're aiming for and how to handle the most common line you'll be fine.

At least with Najdorf the lines I found trickiest were 6.Bg5 lines although that wasn't helped by fact I used Tony Kosten's Easy Guide to the Najdorf to learn theory and author advocated 6.Bg5 e6 7.f4 Nc6? when evals drops from 0.0 after superior 7...Qb6 to +0.8 after 7...Nc6 that lead to me dropping opening as I was getting horrible positions in flawed variation and lost confidence in author.

The Najdorf is not only very deep: 20 moves see above, but also very wide: on move 6
Be3, Bg5, Be2, h3, f3, Bc4, f4, g3, a4, Bd3, Nb3, Rg1, Qd3, Qd2, Qe2
are all viable.

I don't see how this relates to your rating.

If you:

1. Like it.
2. Are a tactical player.
3. Do not mind facing all the sidelines.

Then play it.