There is one advantage of higher voltage. Personally I prefer the a higher voltage and lower amps draw for any given requirement. A higher volatage sometimes means less current draw which is easier on the battery pack which the Internal Resistant of the battery may affect the overall performance. So in the case where the power consumption is 10w, I rather draw 1.35amps with a 7.4v pack instead of having to draw 2.7a from a 3.7v source in which case some battery cannot provide because the internal resistant is the limiting factor. Also less amp draw on the pack means less heat on the pack and sometime better efficiency depending on the application. Then off couse all this will depend on the load and how it is set up for the input voltage requirement.