I've toyed with a cheap 12v receptacle switcher on a cb, and the ac noise was awful. I've been happy with the current alinco dm30 switcher that supports my "shack"; tested back to back with battery, no antenna connected and no difference in noise, though as far as I know AC noise is more of an issue in HF than up in UHF, so if you have an eye that direction, it may be better to make the investment up front in a good linear. My alinco switcher, and some tekpower, have a "noise offset" to move switching noise if it becomes an issue.
Alternately, a lower power linear to support the ~4amp draw of the db20g shouldn't be too expensive if gmrs is all you're after.