Ok, here's a patch that you can use to make Spitfire brakes engage with up elevator.
You can use the same patch to go back to brakes on down elevator (following the prompts when it installs).
Let me know what you think.
I'm thinking ... I like the up-elevator version ... and this is because as you say - as soon as the brakes grab w/ down elevator, the tail comes up.
ps Yes, throttle mix could be setup (not sure how yet), but I'm thinking it's not going to be needed.