Everyone assumes these engines will only work at lower rpm's but they will easily handle a good deal more than 2300. In fact 3000 is not unreasonable to run all day.
If the engine is properly built then there is no worry. There is nothing going on inside it that isn't happening in a V8 that runs up to 3600 all day.
As for a "sweet spot" that is where it feels and sounds good. All engines will vary according to build and application.
