precast floors for new build

Over the next number of months I hope to commence the build of a 2500sq ft two story + attached garage.
I am using precast for first floor. Ground floor will be 900mm+ above ground to maxamise views etc.

I have been advised to use precast for the ground floor due to height I am coming up out of ground.

I am seeking advise on both cost and advantages/disadvantages over poured floor to ground level. Thanks.