> But I would argue that in this scenario, the only way it
> would become invalid is the equivalent of a double-spend... and therefore
> it
> may be acceptable in relation to this argument.
>

The values returned by OP_COUNT_ACKS vary in their exact value depending on
which block this transaction ends up in.  While the proposed use of this
operation is somewhat less objectionable (although still objectionable to
me), nothing stops users from using OP_EQUALVERIFY and and causing their
transaction fluctuate between acceptable and unacceptable, with no party
doing anything like a double spend.  This is a major problem with the
proposal.