Duramax bites the dust - Blown head gasket @ 102K miles

So, after all this controversy, 1. Should you replace the coolant? When they replaced the injectors, they put coolant in it then and we had coolant put last spring when we had 2 new thermostats put in. 2. Should we replace the other four injectors or wait and see if they go bad? I'd hate to start on a long trip with the rv and have that happen again.