TCAS will not issue RA's if ROD exceeds 10000fpm, if your bird can manage that.
IMHO there is a strong case to be made for selecting "TA only" in an ED, in order to prevent a co-ordinated RA being issued between your own and another mode S txpdr. This ensures that all the avoidance will be taken by the other a/c, given that you will not be changing trajectory until below 14000'.
Comments welcome.