Very specific question for people who know Istanbul outside the tourist districts:
I'm attending a convention at a hotel in Istanbul that is in Sirsi, very close to the ring road which has Metrobus express buses around it. Flying in to Ataturk Airport but departing from Sabiha Goekcen (flights booked for me by work travel agent, can't change them). From Ataturk to Sirsi looks like a straightforward Metro then Metrobus trip. From Sirsi to Sabiha Goekcen it looks as if I can take the Metrobus to Uzuncayir and then bus route 16S to Sabiha Goekcen. I can find English-language information on the bus frequency which looks OK, but not the typical journey time. I need to be at the airport by 0930 on a Saturday for an 1130 flight, will catching the Metrobus from Sirsi at about 0730-0800 be enough time? And how easy is the transfer between buses at Uzuncayir, given that I have very little Turkish? Or is it necessary to swallow my pride and get a taxi? I'm a very experienced public transportation user in cities all over Europe, it's just the language barrier I worry about.