If you are skipping the fat sills, which I would also recommend, if you are going with a slap foundation, and placing the sill-less post on the on the slab, make sure you have a substantial footing below the point load/post. In other words don't just put your post on a 4" thick slab. A monolithic slap should be in order. If you are using radiant tubes in the slab take extra precautions to know exactly where those tubes are, you will drill holes in them. Take good photos of the piping before the placement of the concrete and keep the pipes away from the post placement. Plans change and you may have to refer back to those precious pictures.
Steel seem so easy at first glance, but get up close and take a good look. Traditional joinery is easy, really it is. Steel takes far more technology, it was used traditionally but not in the form we see today, with post and beam construction.
