I don't want to prolong this unnecessarily. But it seems to me that in this sort of choice, 'yes, provided that' is logically the same as 'no, unless'. If I am right, to provide two versions of what is essentially the same response would confuse us potential punters. I suppose a justification for two versions might be that, as Mary is I think implying, that those who are at gut level pro ('yes, provided') could be distinguished from those who are at gut level anti ('no, unless'). But I'm not convinced that would be particularly helpful.
Perhaps we might now leave this to Admin? Perhaps s/he might impose a (short) deadline for further comments and then decide whether to go ahead, and, if so, using which questions, on the basis of the views which have been expressed.