I'd go beam and block route as it's easy to do yourself. Can I suggest you talk to the tech department of one of the beam manufacturers e.g Bourncrete, explain your circumstances and needs, and they can then specify what you need so you have peace of mind that it will actually do the job without any guesswork. They routinely design beam/block floor installations to take various categories of floor loadings and partition loads so it shouldn't present any problems (they alreday have the software!) and they'll do it FOC.