The highest rating level you can get away with various openings against.

I thought it might be interesting to discuss the highest ratings you can get away with using each opening against.

By "get away with" I mean that you can use it profitably as one of your main weapons and on a continuous basis, and the opponent knows you may use it, and you aren't getting punished for using it. The level it would hurt if you played it every game, even playing it well. Carlsen throwing in an occasional Italian or Alapin for surprise value is extremely different to using it as a main opening.

By "rating" I mean FIDE rating. I know different time limits also make a difference.

Here's what I've come up with, just from my interpretation, I am totally aware some of them are probably wrong, a little bit guessing sometimes. Feel free to disagree or add your own.

Parham attack (2. Qh5) - 1000

Damiano's defence - 1100

St. George's defence - 1500

Marshall Defence - 1600

Ponziani - 1700

Grob - 1750

King's Indian Attack - 1800

Latvian - 1900

Blackmar-Diemer Gambit - 1950

Goring Gambit - 2000

Nimzowitsch (1. b3) - 2000

Sokolsky - 2000

Owen's defence - 2050

Smith-Morra - 2100

Bishop's Opening - 2100

Vienna - 2150

Evan's Gambit - 2200

Bird's Opening - 2250

King's Gambit - 2300

London System - 2300

Sicilian Dragon - 2350

Philidor - 2350

Accelerated dragon/variant - 2400

Dutch - 2450

Schliemann - 2450

Scandanavian - 2450

Pirc - 2500

Scheveningen (5. ...e6) - 2550

Sveshnikov - 2600

Italian - 2600

Marshall Attack - 2600

Classical Sicilian - 2650

French - 2650

Caro Kann - 2700

QGA - 2700

King's Indian Defence - 2750

Najdorf - 2800

Bongcloud - 4000+

I think the Schliemann could definitely be a lot higher. There's potential in there, especially considering just the sheer amount of prep required as White to stay on top of everything. Even the d3 lines (the "safe and positional" lines) have insane stuff like this:

right away the first entry is wrong, the parham attack is named after an NM who played it a lot.

I would be curious where you ranked the Scandinavian and the QGA?

This is silly. The Italian, Marshall, and Sveshnikov are seen all the time at the 2700 and 2800 level (Indeed, with the Marshall, the only reason it's not seen more is that *white* is avoiding it). And any number of those others make occasional appearances. Just last month, Wei Yi won a masterpiece in a classical game at Wijk aan zee in a Vienna (via a Bishop's Opening Move Order).

The KIA tops out at 1800? Really?!?

Good luck playing the Grob against a 1850. If they are a true 1850 they should know how to take advantage of it.

Latvian - 1900??

You overrated it. Parham and St. George is better.

Where is the London System? 😀

Good point.

I have entered the London System at 2300, this puts it at the same level as the King's Gambit and slightly lower than the Sicilian Dragon and Philidor. This may sound high for a system that a lot of average players take on just to avoid opening theory, however just because of players trying to avoid opening theory with it doesn't mean it's bad, even Carlsen has used it seriously. The main problem with the London System is its drawish nature. But I think if you learned it really well it might be good all the way up to 2300.

I noticed that the Sokolsky opening was not addressed as well.

I'm not too familiar with the Sokolsky. I had a brief read about it and put it at 2000, with the assumption that there is a tangible point to it, like the Nimzowitsch, but not fundamentally flawed like the Grob. If GMs have and sometimes still play it seriously it can't be unplayable at 2000. I also changed the Grob down to 1750 in response to the comment about it.

QGA 2700, Scandanavian 2450.

that sounds fair. I have played it against 2200 rated opponents but it can become quite drawish. I am still curious how you would access the other two openings that I mentioned?

thank you, I guess that i responded before the full edit.

Gata Kamsky (2500+ GM) makes regular use of the London iirc.

@1

This is nonsense. Most of what you listed has been succesfully played in classical time control games by top grandmasters.
Bongcloud is a joke and is only for bullet troll games.

I guess 2900? Hikaru gets away with these openings 😂

I already addressed how using it as a total surprise is not what I'm talking about.

I believe Hikaru was trolling or having fun even in classical, a lot of fame these days is caused by being outlandish and getting in the chess news, becoming a chess personality is a lot more lucrative than actually being that good at chess these days.

I suppose you mean a computer evaluation, which often means very little in human terms. A human evaluation of equal or "close to zero" is disastrous for a white opening. GMs win about twice as much playing as white as they do as black. 

@18

"A human evaluation of equal or "close to zero" is disastrous for a white opening."
++ No, that is not true. All good black defenses end up equal or close to zero.

"GMs win about twice as much playing as white as they do as black."
++ Black has more ways to err than white.