As long as you move enough of the root system, the better because you minimize transplant shock. It is more difficult to cut a lot of the root system when the camellia is -for example- a 300+ year old tree so, the younger they are, the easier they are to transplant.

I have moved smaller plants (under 4-5 feet) many many times with no ill effects. That being said, I would suggest you pot your plants up until you make up your mind where you want them. In pots, you can even put them in various locations around your garden to see how they like it. Anyway you slice it, it's far easier to only dig one hole. :)

Do be sure to mix plenty of peat moss into the planting holes. When I planted my very first ones, I didn't know to do it. They didn't die, but neither did they thrive. The ones that have been moved and treated to the peat have taken right off in growth.

I have a plan where to plant my new purchases. But just in case things don't work out and I need to move them, it is good to know that they can tolerate the move when it has to be done. Thanks.