David: looking back at the mailing list ~ 28/Mar/12 it's not clear what exactly was the problem that required reverting at the time ... where the test failures even caused by this specific issue, or something else that you committed right around the same time?
Given that we've already created the 4x branch and started pushing towards Alpha, i would at least move forward with making sure trunk & 4x are on parity with 3.6 in terms of the changes to the example and the log/error messages.
Depending on what the issue was with the tests we can figure out how we want to move forward from there.
I take issue with the Yonik's comment "we're not really gaining anything with this change". ... I don't think defaultSearchField & defaultOperator have a need to exist, let alone exist in schema.xml, thereby creating unnecessary complexity in understanding the product – albeit in a small way.
I think the question is "if we stop promoting them in the example, and start encouraging an alternative instead, what is gained by actually removing the support in the code for existing users who already have them in the config and upgrade?"
It's one thing to say in CHANGES.txt "we've removed feature X because doing so allowed us (add feature|fix bug) Y, so if you used X in the past now you have to use Z instead" but there is no "Y" in this case (that i see) ... we're just telling people "we've removed X because we think Z is better, so if you used X in the past now you have to use Z instead".
You may feel it's a complexity for new users to understand why these things are in schema.xml – which is fine, but isn't removing from the example schema.xml enough to addresses? What is the value gained in removing the ability to use it for existing users who already understand it? This is the crux of my suggestion way, way, WAY back in this issue about why i didn't/don't think there was a strong motivation to remove support completely in 4x - an opinion echoed by Yonik & Erick.
As evidence from recent mailing list comments by folks like Bernd & Rohit, there is already clearly confusion for existing users just by removing these from the example – let alone removing support for it from the code.