Nothing in life is perfect, and neither are staves. If properly done (like Beyond Barrels Bottle Aging Staves, and the staves used to make Makers 46) staves can produce excellent results, in some cases better than what could be produced with a barrel. They do, however, have their limitations.
The primary limitation to using staves has to do with oxygen. You can break down all the reactions, biological and chemical, that make up what we call "aging" into ones that require oxygen (aerobic) and ones that don't require oxygen (anaerobic). Everybody reading this has thrown a dry stick into a lake before and seen that it floats. This is because the dry wood is filled with air (oxygen) in-between all of the tiny gaps in the wood fibers. After about 4-5 months of being submerged, staves no longer have any oxygen left inside of them since it has slowly been used up and replaced by whatever liquid it is submerged in.
As the stave runs out of oxygen, only the anaerobic aging reactions continue while the aerobic ones cease. When this happens a bitter note begins to show up in the finish of the flavor profile of whatever liquor it was used on.
Most of the aging "magic" happens inside of the wood, where the wood meets the alcohol and air. In barrels there is always air coming in from the outside, and liquor coming into the wood from the inside, thus both anaerobic and aerobic aging reactions continue nearly infinitely.
So, for any instances where you want to age something longer than 4-5 months, using a large (20+ gallons) barrel will work better (assuming you find one made of wood weathered for at least 6 months), in all other circumstances, properly done staves can produce superior results. ..however, if you are willing to take the staves out to air dry for a week or two every 4-5 months, you can use staves to age liquor for years.
The other downside of using staves is that you need to let them air dry for a few weeks in-between uses. This is also related to oxygen. Air drying the staves in between uses lets oxygen (air) get back into the stave, so when it is reused, both aerobic and anaerobic aging reactions can occur just as they did for the first use. Barrels do not need to be air dried in between uses since they always have oxygen present inside of the wood. On a positive note, this air drying process allows the "bad stuff" that the wood fibers trapped to off gas, letting them filter more effectively on subsequent uses. If you let a barrel air dry, often it will crack and it will no longer hold fluids as well as it used to.
The good news is that re-aging a brown liquor and aging a cocktail never takes more than 3 months. Most aged cocktails are done in less than a month! Try it out today!