Dont go assass until you have tier and Archi trinket. Combat is doing very well in cleave fights this tier (as usual). You only really need to play sub in 2 fights (reaver/zakuun).
You can start playing Sass there isn't a big difference in damage for assassination and sub this tier ( right now ) A lot of the fights are practically made for assassination.
I think he is asking for if it is a gain to replace tier 17 4 piece proc with some HFC HC gear that is then going to break the 4 tier proc.
I am wondering so myself, honestly I don't think it is worth breaking the 4 piece bonus unless you can go straight to 2/2 piece proc with T17 and T18, but I am not sure....