Mixon, C. Kirk for D. Henderson and Herbert

I’m getting this offer in .5 point super flex.
I don’t think I really want to give up my Herbert but will if I got a better weapon than Christian Kirk. I already have Josh Allen and Kyler Murray as my other 2 QBs.
My RBs are: CEH, Jon Taylor, Josh Jacobs, Justin Jackson, Darrel Henderson, Alex Mattison.
WRs: Michael Thomas, Adam Thielen, Allen Robinson, Will Fuller.
TEs: Fant, Jonnu Smith

What if I counter with AJ Brown and Mixon for Herbert and Henderson?