When it comes to dabbing, bigger in fact is not better. Dab rigs, juxtaposed to bongs, are specialized rigs made specifically for smoking concentrates such as shatter, oil and wax. Of the many reasons dab rigs are usually small in stature the main ones are: improved flavor, ease of use and portability.
When taking a dab it's crucial to inhale the vapor as soon as possible. With a smaller dab rig and smaller water chamber the overall distance the vapor has to travel is minimal. This short distance is important because said vapor has less of an opportunity to cool and condense, which leads to a more flavorful experience. When cold air hits your vapor is zaps flavor from it. Which is odd because when smoking dry herb through a flower bong the more percolation and the more room you have the better the toke.
Ease Of Use
Dabbing is harder than ripping a bong, so let's not make it any more difficult than it needs to be. In short to take a dab you have to heat a quartz banger, let it cool, add the wax, add a carb cap and rotate the carb cap around as you inhale. Smaller rigs are easier to handle, especially when using torches to heat a nail. With all these moving parts and different actions disaster is always one clumsy move away. Whereas with bongs it's fill bowl, light bowl and inhale. Using a smaller dab rig reduces risks of accidents, takes up less space on the required flat surface and allows allows you to stabilize the rig and heat the nail with one hand while holding the concentrate with the other, making the process much more manageable.
Rather self-explanatory, but smaller dab rigs are easier to travel with than larger ones. Whether you're taking your rig to a friends house or blazing the trails a smaller dab rig is easier to travel with and has a significantly lesser of a chance to break.
Lastly, cash rules everything around me. Pound for pound dab rigs are more expensive than dry flower water bongs. Opting for a smaller rig can help save money while providing a better experience