The user of-course can already implicitly work out this information from comparing the fee-rate with the actual fee.

I think that it would be useful for people not wanting to do this arithmetic in their head.

{
        return (nValue < GetDustThreshold(minRelayTxFee));
    }
    friend bool operator==(const CTxOut& a, const CTxOut& b)
    {
        return (a.nValue       == b.nValue &&
                a.scriptPubKey == b.scriptPubKey);
    }
    friend bool operator!=(const CTxOut& a, const CTxOut& b)
    {
        return !(a == b);
    }
    std::string ToString() const;
};
class CTxInWitness
{
public:
    CScriptWitness scriptWitness;
    ADD_SERIALIZE_METHODS;
    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion)
    {
        READWRITE(scriptWitness.stack);
    }
    bool IsNull() const { return scriptWitness.IsNull(); }
    CTxInWitness() { }
};
class CTxWitness