Jmo, but I don't think it's off at all. I'm hearing good things about SR 71 & I'll looking forward to trying it but I've always loved Bramble. It's possibly my favorite BCBS variant.
I have a feeling if you are posting FT: SR-71 and are ISO: Bramble, someone will take you up on that offer very quickly. If you did the reverse, looking for an SR-71 and offering Bramble, I am not so sure you would get any takers (@JavaNoire notwithstanding ). That said, it's reasonable enough to offer as a 1:1 if that sounds fair to you, and see what happens.
Bigdaddypolite, I could be wrong, but I think when the initial frenzy calms, more people will see the offer as both reasonable & attractive. I haven't had the SR 71 yet & I am looking forward to it but I expect the current demand to cool considerably.
SR71 cooled off a bit since its release. I think you might have a little trouble if you're on the Bramble side still as of right now. You never know though, someone might need Bramble to complete the BC Variants collection.