Definitely still relevant. Eliminating ambiguity with every 'end user' is the goal but ultimately sacrifices usability to some degree.
I believe the following configuration eliminates all ambiguity while fully preserving usability.
The ambiguity arises when we add the second checkbox.
Another option would be to remove the "Send as zero-fee transaction" checkbox altogether and leave the "Pay only the required fee" option. Then we would allow the counter to be rolled back to zero preserving the zero fee functionality just making it less obvious.

One thing's for sure, we don't want any zero fee option available to the user unless they enter the custom settings. Most users should use the client's default fee settings. The custom settings should be used by advanced users only.
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We'll probably want to make a decision on this sometime this week unless we want to delay the new client further.