You CAN have both - low noise AND high efficiency
For noise-critical portable applications, such as GPS receivers, connectivity, and sensing, power supply designers always had to choose between longer battery run time (from higher efficiency) or higher signal chain performance (from the increased sensor sensitivity possible with a quieter power supply). For line-powered industrial or communications equipment applications, designers have been forced to dissipate significant amounts of power in LDOs to achieve the desired noise performance. Achieving both low noise and high efficiency was impossible. Now for personal electronics, industrial, communications equipment, or medical applications, this has changed. New advances in low-noise DC/DC converters as well as LDOs provide low enough noise with high efficiency.