Having read this thread as well as others on Ankermi before going to Maumere (on SB and Tripadvisor mostly good experiences, on Lonely Planet mostly bad), I thought I'd weigh in after just finishing up diving with Ankermi so that others can also use it as a reference. I won't do it as a new posting "trip report" as it was only 4 days worth of diving and only part of a much larger trip. Unfortunately, I had a pretty poor experience, with some of the same reactions from Kermi that the OP related.
I'd opted to stay at Sea World as for roughly the same price I seemed to be getting a nicer resort along with free airport transfer, wifi, and the ability to pay by credit card, all of which Ankermi didn't have. But Sea World said they rarely went out on muck dives and, since I love muck diving, I decided to stay at Sea World, but rent a motorbike to go to Ankermi every day to dive. It also seemed that Kermi was somewhat of a "local legend" as a spotter and guide, and I was looking forward to diving with him and seeing lots of cool critters to photograph. Although in booking everything Ankermi seemed strangely fixated on the fact that I wasn't also staying there, when the time came near to arrival they said they only had a couple of guests and they were avid muck divers, so barring any problem with weather, I could come over there and do muck diving every day. On the first day, Kermi changed his mind about going on the last dive after agreeing to it in the morning, something that was going to be a theme. He instead said I could just do a solo dive, which I did. But then the same thing happened on the second day after the first dive..with no explanation..i was told if i wanted to do another dive I could do it with another guest who was staying there. Based on what had happened, when the third day came, I asked three times in conversation about if he was "sure" he could do a third dive that day and he said yes, no problem each time. But then when it came time for the dive, he again asked me to dive with another guest as my buddy. Even though we had agreed to it at the beginning of each day and/or the night before, this occurred each and every day. Disappointed, but understanding that things change even though I was given no explanation, I had "rolled with it" each time, although I was beginning to feel taken advantage of. Then for my last day, after earlier in the day talking about what sites "he was going to take me to tomrorow", I was told at the end of the day before that since he needed to pick up his wife at the airport the next day, I'd be on my own to dive alone on the house reef. There actually wasn't even a flight from Bali in the morning when I was to be diving...despite it never being discussed that he was going to have to change his plans on my last day, he could have easily dove with me in the morning and picked up his wife from the airport in the afternoon. At the same time he gave me the bill for the couple days of diving, and I noticed I was being charged full price for my solo house reef dives and dives with the other guest and decided that we finally needed to have a talk. It was one thing for him to change his mind every day after committing to something else earlier leaving me to dive on my own, but it was another thing to charge me full price as if he was there! Although I asked to talk to him in private away from any other guest and did explained my position calmly, he really flew "off the handle." Among other things, he said his wife had told him "I was going to be trouble," again for some reason mentioning that I had chosen to stay somewhere else, that no guest had ever had any problem, and it was "his place, his rules." Although I was never threatened like the OP stated he was, the manner in which I was spoken too was rather threatening, and the things being said I could only best describe as being childish. I continually got told off for about 5 minutes until I'd enough of it and just started packing my gear to leave. I told him, honestly, did he think a guided dive should be priced the same as a solo house reef dive, especially when his inexplicable last minute cancellations forced the dive to be solo anyway? I told him of course in diving with 100s of dive ops that has never been the case, but if it were, why wouldn't be post the price for this or tell me it was the same somehow? While it's true I never asked, it's also true that the solo dives were last minute due to unexpected cancellations on Kermi's part. He then told me if I didn't want to pay the full amount, I couldn't dive the next day, since I felt "I had to dive with him." He just somehow didnt get how diving with an experienced dive guide as promised should be any different than diving on one's own. As a very experienced diver, I have really minimal needs...again just want a guide who will find stuff for me to photograph. I have no problem adapting to last minute changes (although not every day) or diving solo, etc...but NONE of this was ever planned or discussed...and this was through no language barrier or other misunderstanding. I may have had a poorer experience from a service and professionalism standpoint in all my years of diving, but if I had, I can't remember it. Make your own decision about diving with Ankermi, but I'd pass on it and stay/dive with Sea World. It's too bad...Ankermi as a resort is nice enough, if fairly basic, the food is better than at Sea World, and he has a nice and friendly staff. On the dives he actually goes on, I had no complaints with Kermi as a guide...diving wasnt exceptional but he appeared to work hard every dive to find stuff.
One other thing to watch out for if you do decide to dive there is how they do their pricing, something else I haven't seen anywhere else that I've dove with. They price in euros, something many ops do, and they accept other currencies, also like most ops do, but if you DONT pay in euros, they price on what it will cost them to convert your currency TO euros, even rupiah! They also don't post these rates, and it's a huge difference. One shore dive (with your own gear) is 20 euro, or the equivalent of $26 USD right now...but the USD price per dive is $32...a more than 20% premium per dive. So make sure you have euro or can pay in rupiah, which isn't at least a 20% mark up.