sorry, but you did ask !
I did ask and you responded my love. Therefore there's no need for an apology and you have confirmed what I already thought. NIce to hear it from such a qualitative and respected source.
Not sure where you're based Stephen but I have both a Sigma and a Tamron 28-300 Canon fit and if you're nearby, you're welcome to borrow one or the other to give them a try. The Tamron's actually already on loan until the end of the month, but I wont need the Sigma until October when I'm going to the Atlas Mountains with Sian for her 50th.