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 a.hash != b.hash;
    }
    std::string ToString() const;
    void UpdateHash() const;
};
struct CMutableTransaction
{
    int32_t nVersion;
    std::vector<CTxIn> vin;
    std::vector<CTxOut> vout;
    CTxWitness wit;
    uint32_t nLockTime;
    CMutableTransaction();
    CMutableTransaction(const CTransaction& tx);
    ADD_SERIALIZE_METHODS;
    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
        SerializeTransaction(*this, s, ser_action, nType, nVersion);
    }
    /** Compute the hash of this CMutableTransaction. This is computed on the
     * fly, as opposed to GetHash() in CTransaction, which uses a cached result.
     */
    uint256 GetHash() const;
};
int64_t GetTransactionWeight(const CTransaction &tx);
#endif