I think it is a consideration all classical guitarists have to make a decision on at one point or another - whether to use a (traditional) footstool or to use the relatively newer invention a guitar support.
Years ago when I started playing the classical guitar, there was no such issue. We were all taught to use a footstool (see below):
It was something that we all (students learning the instrument) had to get used to. I remembered it was a little bit uncomfortable at first, having to "prop" up our left leg and remain in what was seemingly an awkward position while playing the guitar. But that discomfort was soon overcome, and when the music begins, one can't help but forget about the little device sitting beneath our left feet.
Still, having your leg raised above the ground for anything more than a hour or two, and you could still feel a little strain/stiffness on your back.
It was only in the recent 6-8 years or so that the guitar support made its way into the local guitar community (at least in Singapore.... it could have been a bit earlier for the European/American community, which tend to be the early adopters of such changes). I remembered that I bought a Gitano guitar support just to "test it out", and see if it really was more comfortable than a footstool.
It turned out to be a good experience (overall), and since then I have performed using the guitar support more often than not. This is not to say that I cannot revert back to using the footstool, sure I can. It's just that given a choice of having to raise a leg/foot up artificially, compared to raising the guitar up artificially (both using a prop, hence "artificially"), I tend to prefer the latter.
Still, with my new guitar on its way (hopefully in November, as promised... *fingers crossed*), I am a little concerned if the constant usage of the 2 suction cups of the guitar support might just affect the layer of polish/lacquer on the guitar surface. Looking at my old-reliable Kohno, it seems to be "eating" away a layer of the french polish which was not-too-long ago replied onto the aging instrument. Using a footstool would solve this problem.
Anyway, as luck would have it, my Gitano support is also showing signs of wear and tear - rusting at its sides, plus the suction cups are dropping off all too frequently these days, and I have to readjust their positions, sometimes mid-way of play. Perhaps it is time to reconsider going back to the footstool?
Hmm... the vain guitarist that is me has now turned to surfing the websites for a nice footstool, not just some metal-looking piece of scrap that you mindlessly tug under your feet. But rather, a elegant, designed piece of guitar "furniture" (as classified by a certain guitar website).
Here's what I have found:
Sexy~~~ But also costly. Imagine paying upwards of US$200 for a footstool!? Oh ok.. for a guitar furniture. =)