If you can stick with DC only operations it will indeed be much more efficient. Not losing watts converting 12 VDC up to 120 VAC and then back down to 12 VDC. Probably using DC/DC converters all the way.
Sine wave inverters create a PWM (pulse width modulation) waveform through the switching transistors and amplifier to create an approximation of a sine wave. Even so there are harmonics created by the transistors switching through rise/fall. This can generate EMI up to tens or hundreds of KHz. Be prepared to deal with some interference, particularly at the lower bands like 160 and 80 meters.
Switching supplies (AC/DC) work pretty much the same way. They rectify the incoming AC power and then run it through a pair of transistors at a much higher frequency (tens of KHz) and use a tiny transformer to step the voltage down, run it through a bridge rectifier/ regulator, maybe a filter cap or two and then provide a DC output. The advantages of switchers are that they can be fairly efficient at low loads, small because the transformer is intended for high frequency operation (the same reason that aircraft use 400 Hz power systems). And with less loss due to heat.
Other than my boat-anchor radios I run everything off of 12 or 24 VDC with batteries on float charge. The chargers are linear supplies (no switchers). Even my shack lighting is 12 VDC.
[FONT=Comic Sans MS][SIZE=2][I][COLOR=Red]Ms.Tisha Hayes, AA4HA
The grid drives all of my gains.