We put in a timber floor that had the engineered trusses made for us by a Carlow Co. Approx 2000sq feet and cost was €4k or so. It is completely squeak free compared to what a 'carpenter would have put in' (this is hearsay BTW, suppose it depends on his attention to making it squeak free). Double slabbed the kitchen/living room to reduce noise as that will be the busiest room in house and used thicker ply upstairs, plus for insulation (there is six inches of it in the ceiling/first floor). Does this come by default with the concrete?
Reason we didn't go concrete was just a personal dislike of it.
One benefit is that you don't have to use extra materials in the foundation, which apparently has to be done if using concrete in upstairs floor. Plus it is nice sensation underfoot compared to concrete. However the costs in the foundation are probably offset by the costs of the ply etc with the timber.
Very satisfied with it too, gives me the sense that the house has an older country feel as opposed to mass concrete. Have always lived in houses with timber floors and never found the noise an issue when done correctly.