Ah, thank you for the clarification. I never experienced a freeze with ice on 10.13(.1), I terestingly. I gave it a try on my system, though, and it seems like it boots significantly faster with that option (I never used that card with Sierra though so I’ve got no way to compare).
I can confirm that bootup/sleep/wake is significantly faster by adding -rad4200. Additionally the fan dosn't spin up to full speed anymore after wake. Thats good.