I'd argue that an opiate naive individual on 10g of red vein would be feeling VERY mad nice, considering that dose has me, not opiate naive, feeling mad nice. Definitely at the very least as strong a feeling as codeine
someone like that should start with just a few grams, approximately a teaspoonful. it's also normal to not feel anything at all the first few times you take it.
for someone opiate dependent, that dose is enough to halt the physical symptoms of withdrawal and alleviate some of the emotional symptoms, albeit for a short time. if you want to quit opiate abuse badly enough, that's just about all you need.