needs to be done in a way that does not sacrifice good UI principles.
I agree with you, @tomsmyth but in this case, the new feature is completely optional and requires user action to trigger (setting an SMS receiver in settings). I think adding SMS send support with the proposed new UI as an experimental feature will give an opportunity to get feedback on that UI before it gets rolled out to the more common HTTP sending. Initially I expect few organizations will be set up to receive SMSs and we can work specifically with those to get feedback.