Yes, I don't see a reason to get rid of SSR weapons. It's not like there is a Weapon Orb store. I use Ygg Lance to reliably solo Ult Water, despite it slowing things down quite a bit.
Though, with the (potential) ridiculous amount of HP your Grid has, I doubt you'll ever need it. 30% from Dartagnan and 40% from dual-skill weapons? I don't even know what the mid top one is. That might be HP too.