I think there are a couple of important points:
* There are still elements that VE can't edit;
* There are still pages that render incorrectly in VE;
* There are still likely other bugs, roundtrip and performance issues that
will frustrate users.
We do want to eventually get all users to use VE, but we need to be
realistic that at this point we're launching beta software that has lots of
quirks, some known, some unknown. It's awesome already but there's still a
long way to go.
That means power users will have _legitimate_ reasons to want to continue
to use wikitext for some time; it'll be more efficient in many cases, and
sometimes necessary.
I want us to be careful to not message in a way that glosses over such
concerns.
I'm personally fine with the preference as an option, but we need to make
sure that power users know about it. I can see the concern about a
secondary "edit source" option from a UI cleanliness perspective, but
again, recognizing that VE is still beta and will be for a while, I think
James' argument that this may well be a better way to get power users to
continue experimenting with VE (rather than disabling it in the preference)
has significant merit. It could be deprecated once VE has built-in source
mode switching.
Erik
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Erik Möller
VP of Engineering and Product Development, Wikimedia Foundation