I spent a great deal of time profiling Artemis to ensure its design wasn't bottlenecking the performance, and I did not find it lagging behind its OOP alternatives, e.g. dozens of thousands of entities.
What you did with Artemis especially considering the experimental / trailblazing aspect is a complete success. For the type of games (2D / platform) created with Artemis it works well. I was very impressed when I checked out Naturally Selected 2D running on an iPad2 which is the lowest specced device I've tested with so far.
Any discussion I'm contributing to here is more or less aimed at floating ideas around future directions. Saying that Artemis is a really good "type I" ES does not detract from what was accomplished.
If you have more than a dozens of thousands of entities, hundreds of thousands, then you're doing something terribly wrong. No game should have that number of entities active in its world at a given time.
All I wanted was a easy design, where I wasn't schizophrenically dependent upon some hierarchical OOP structure and was fast enough.
But that doesn't mean Artemis-design is suited for all. It's quite rigid when it comes to how entities are composed.
I think you could say.. No 2D game should have that number of entities active in most usual game play scenarios. All of the Artemis related games I got to compile surely fit those assumptions.
For a 3D game that is partitioning a larger world including partitioning the ES then entity counts could be in the hundreds of thousands (let's say ~15-20k per region), but of course in most situations only updated for regions near the player(s). The design I'm working toward is meant to support a larger general use case, so the additional data oriented packing and efficiency will make a difference. I'd say a fair assumption about "type II" ES is that new architectures are less rigid and increase the throughput and conceivable data parallel aspects of the ES out of the box. In the case of my efforts integration into the larger engine architecture is much easier since the CA relationship is inverted with the CA being a superset of the ES.