@Arvolear in case of eliminating hashing out of add, update and remove node transactions you may save gas even more.
E.g. Poseidon hash implementation in circomlibjs for 2 and 3 uint256 elements take 54K and 70K gas respectively. If I’m not missing something the hash recalc is done for each of those 3 methods up to (!) the root. Then, gas saving may be essential, unless the hash function is very cheap or introduces as EVM precompile.