Let’s move beyond ‘who the Average Piper is’ and talk about the ‘end goal’ and that is to play music. The most basic element of the music is the sound that your instrument produces. The sound is a product of many factors. The bag, your choice of drones, reeds, chanter, chanter reed, how it’s all set up, and how you blow it. There’s also the climate where all this comes together. I’ll begin by stating that it’s complicated…but entirely logical.
The bag is not only a reservoir for air, but it’s also an important element in how your drones sound and behave. It is the foundation of the instrument. If your bag isn’t right you will compromise the sound and behavior of your instrument or you will needlessly complicate it.
Gor-Tex bags are relatively inexpensive, light in weight, and fold nicely when stowing your instrument. The trade-off is that they provide little in the way of moisture control without add-on systems installed inside. Also, it can be challenging to achieve “clean” starts and stops.
Hybrid bags provide better control and other benefits. They too require mechanisms inside to manage moisture. Because of the materials used, a hybrid bag will maintain its original shape throughout its lifetime. (Hide bags tend to conform to your body shape)
Lastly, rubber grommets to hold your stocks place are standard on all synthetic bags and optional on some hide bags. Beyond the initial installation of the stocks, they provide no benefit or advantage. Some pipers consider them a “net-negative” in that they inhibit full-resonance of your drones. They can also make stowing your bagpipe in its case difficult.
Understanding these nuances will help you to make decisions that are right for you.