I do not know wat HAVOC is but I can tell you the following; I use the standard SL viewer, I applied a subdivision modifier to my work but that is already on the object and the 17329 verticles in blender is the result of it, I export with blender via export:collada(default), and choose operator preset SL+Open sim static and export to SL/opensim in the options menu and I have done nothing else but choose upload:model in Sl itself.
Edit: Also in the export menu op blender is a "use modifiers" option but unchecking that one does not make a difference