I'm sure there are plenty of people that have somehow slipped but I suspect it would more likely be if someone was walking in the bathroom with socks on but whatever the reason, it has been considered for years that high gloss tiles are dangerous in what is called a wet area but I can't disagree with you that a mat is all that is needed to stop from slipping with wet feet but of course people have slipped in the bathtub too because it's so slippery so the jury might still be out as to how to make a bathroom totally safe. I think it's just a suggestion based on some kind of trials and my theory is more hand rails where possible.

It can either look really dramatic or too dark, depending on the size of the room as well as your other components. I've attached a couple of images of our work using dark tiles, the smaller bathroom we have surrounded the bath with dark tiles but then balance it with an extra large mirror to bounce the light around the room. The larger bathroom we have taken the floor colour way onto the wall but used a different texture on the walls for drama. Hopefully this gives you more of an idea but you shouldn't to nervous of the room being dark, it's where you can create a contrast as well as textures. Look forward to seeing what you go with in the end.

if the budget allows for it, porcelain tiles are my recommendation. They look better, have smaller grout lines, can get them to look like any modern stone, like marble, granite, travertine or even available in wood look slats. My hot tip is the less grout the better, which means the smaller the tile the more grout lines, stay away from mosaic on the floor, I've seen too often these being ripped out because the grout dates and ages from soap scum etc. After seeing grey, black and various colours on floors, I would always go with white on the floor, easy to keep clean and no fading of the tile profile. Good Luck!!

I would recommend going a darker colour too! We have done it several times with clients who (like yourself) can't see what the finished concrete aggregate will look like until afterwards and the darker the better we have found. Like Zaffa said, it would be amazing if you could extend the concrete into the bathroom, as that can be absolutely beautiful and this aggregate look is a fantastic addition to a bathroom. However if you want to break it up I would go for a dark charcoal (large format) tile so you don't risk clashing colours. Darker bathrooms are really stylish so you don't risk sacrificing on style. Don't hesitate to contact me if you need any help selecting specific tiles as we know how overwhelming it can be and are happy to help. Best of Luck, Jordan from JFI Studios!