If you haven't gotten a biz plat SUB, open a new one for sure. I got a plat last summer, got the 100k MR for 10k MSR, then got an offer this spring to upgrade my biz green to ANOTHER biz plat for 50k for 5k MSR. So at the moment I have 2 Biz Plats in my wallet (and over 1k in AFs!) but I'm going to downgrade my OLD plat to a green. Who knows- maybe I will get to upgrade it to a Plat for points later on!
To answer your question - no benefit, unless you're ineligible for a SUB on the biz plat because of the once per lifetime language.