My Tb has hoof boots on at home while hacking (cavallo simple boots) as he struggles with rocky and stony tracks, but when competing or working at home (i showjump) its either going to be on grass or in an arena and so i find he doesnt need them at all.
I'm barefoot (well my pony is!) and don't need boots, however I saw someone popping round the SJ and XC at a ODE last weekend in a pair of old macs hoof boots. Pony seemed very happy and no slipping (some shod horses were having problems). It wasn't high only 2'6".
I do sometimes. I do endurance. If the ride has a lot of canters then I don't boot because my boy tends to flip the near fore off, that said they are a year old now and were used constantly in the transitioning period. I only ever use Easy Boot Gloves. There are many unshod horses in the endurance world and use either nothing or glue on's, Boas, a variety of Easy Boot's, old Mac's, Jogging boots and equine fusion's. The list of different makes is vast. You will find them all on google but don't buy any until you know exact;y what size you need.