Replaced the fans - couldn't be happier with the result... I just bought a 3pin and 4pin JST connector and soldered on a standard PC fan header. Note that the fan wiring is different to PC fans but the cable colours are correct - yellow for tach, black for ground and red for +12V. Also there is no space for 120mm fans on the inside unfortunately.
Also drilled a bunch of extra holes in the case to allow more air to flow though and added an additional fan with a splitter on the other side to push air through.