Those who generally decide on the backless bar stool option do so mainly for the way it looks and not for the practical purposes.
This is grand if you do not plan on using the stools very often and only plan on having the stools for show, either way care must be taken when weighing up all the options.
On one side, a backless bar stool is generally lighter than those with back rests. Having backless bar stools in the home, it doesn't matter that much about the weight, but for industries such as bars and restaurants this could be a major advantage for staff or customers.
As a backless bar stool is lighter than a bar stool with a back rest, it can be moved far easier which is very useful if furniture needs to be relocated quickly or there is an emergency. It is for this reason that the backless bar stool is favoured over those with backs, now if you to also add a swivel action to these stools you would then have yourself the perfect bar stool.
But if you looked at this a different way you would notice that after a while sitting on a backless bar stool could cause some level of back pain. It is so easy to forget that people really do need to have some sort of back support; this is something that should be considered before purchasing. Not being able to relax when sitting on a bar stool would become a hassle to those who have even the strongest of backs.
An additional disadvantage when procuring a backless bar stool is unambiguous it may give off and could be deemed to have a very bland and boring look. A lot of bar stools are very creative and stylish pieces of furniture, but these stools are usually made with back rests. Now I'm not saying that buying a bar stool with out a back rest is bad thing, it just narrows down the number of stools available to purchase.
When all is said and done buying a backless bar stool presents no real advantage. What it really boils down to is, where are you putting the bar stools and how often are they going to be used? It's really up to you so choose well.