Like many on the site I have used single, double and treble sticks. I think a great deal of which if any you use, depends on where and what you are stalking.
I have always used a single stick on the hill for Reds. It is a good aid for walking, support for the spotting scope when glassing or using binoculars to glass at distance, and I have used it a number of times as support when shooting kneeling down. However a bipod can also be useful, which I use to a considerable extent on hind culling.
Where the double and treble sticks come into their own is in woodland stalking. It is very true that a good pair of double sticks can be used, and is the general ideal for many. Africa they are common place, normally held together with a piece of inner tube, or leather thong.
The treble sticks I use a good deal when taking clients out. I find they are very good when standing and waiting, although they do have disadvantages in that they can be rather cumbersome when trying to set them up in a hurry, whilst a double set of sticks is easier. They also tend to loose bits, like the rubber feet, and the occasional screw so the leg falls off. They are also a bit expensive for what they are, and can be a bit difficult to pull the legs into place after you have had them for a couple of seasons. However a squirt of silicone usually does the trick.
What I have noticed with some clients when they use them is that they hold their hand over the barrel near the fore end, and if it a free floating barrel it will make a difference to the shot placement.
In general I quite like the treble sticks and doubles, as you can bet your bottom dollar there is never a convieniant tree and branch to shoot from when you are woodland stalking.