I think the consensus is that if you have the 981, the 718 isn't enough of an upgrade to be worth the significant price increase. You could probably find a 991.1 GT3 for around the same money as a new 718 if you are cross-shopping. Also, the 981 is more rare, and a bit less refined, the latter may offer a more visceral experience. Also, the 981 sounds better if that's important to you.