I have two as well, and both work well. The newest one, I disassembled into about 50 pieces, and managed to get it back together, and you'd never know it was apart.
I recently purchased a Service Manual, and I recommend it for any serious amateur. After taking one apart, looking over the circuitry, operating one mobile for nearly 5,000 miles, I have a few insights.
If you use proper wiring techniques, and you don't over-drive the radio, and you are in motion (engine running), you don't need any voltage compensation (i.e.: W4RRY booster) to achieve a clean output. Using one doesn't hurt, but is is a waste of resources.
The same goes for filtering too. I am aware that the European versions have an requisite filter for DC operation, but I don't believe it is at all necessary for clean operation. If you take time to look at the schematic of this filter, you know why it (and others) is superfluous.
I never switched the DC power from my 7000, or any other radio I have EVER used mobile (solid state or tube). I can't remember any problem that is caused, or might have caused. In fact, switching power on and off most likely would cause more problems, not less (spikes etc.).
There are those that feel automotive starting motors cause enough impressed spikes to elicit all sorts of failures including those in the final circuitry. If this were the case, you be reading about it all over the net. You don't.
The areas of mobile operation which need special attention are proper antenna mounting and feeding; adequate wiring and fusing; all manner of bonding; and in about that order.