Salam to everyone..
Dear Vinny,
It's correct that your keris dressed in Yogyakarta style, Gayaman for sure. The Gayaman is considered as informal sheath in Java, which is used daily. The mendhak is Surakarta/Solo style. The hilt and pendhok are also Yogyakarta style. In my opinion, the blade is much older, perhaps from Tuban or old Madura era, around XV-XVI century. The pamor is beras wutah, and I also agree that it has the beautiful (and some believe, powerfull

) Akhodiyat pamor. For the dhapur (blade's shape), you should look carefully for the Tikel Alis (shallow groove which shaped like the eyebrow, located right upon the Gandhik/pejetan just before the sharp edge. "Alis" means, in fact, eyebrow). If the tikel alis presents, then the blade is Tilam Upih, if it is not, then you're right, it's Brojol.
Rick, your keris is what it's called in Java as "Tangguh Lempoh". Lempoh (javanese language) means lumpuh (Bahasa/Melayu) or crippled, in english. It's called so because the attribution (tangguh) could be judge undoubtly, so there should be only one attribution judgement for keris with "Tangguh Lempoh", which means, The Tangguh cannot "walk" to other era anymore

. And yours is attributed to Sultan Agung era, Mataram Islam Kingdom.
Nechesh, it was also Sultan Agung who forbade the use of ganja/gonjo sekar (ganja with "flower", which is, the pamor), except his immediate families or high-rank court officials. But the use of ganja wulung (wulung means black, that is, ganja without pamor) is not always because the empu or keris' owner obeys the king. It might be caused by the original ones has been damaged, which may happen long after the keris was made. All in all, just look for the workmaship, which is the one you can always rely on.
I do apologize to everyone here, because I haven't get the pictures of my collections attached. It's always blurr, maybe because I only use digital camera from a handphone