"does the radio have a sleep timer ?"
Yes, called a 'Time Out' timer. After so much time (setable) it turns it's self off.
"is filtering possibly better then icom'mk2g...?"
Possibly better? Don't know, but it's just as good anyway.
"can display brightness be turned down for night use ( so its not blinding ) ?"
Yes, several 'stages'.
"is the unit acceptable installed mobile, QSO's possible while driving?"
Yes to both. I've used mine mobile. There are several aspects that are debatable depending on your likes/dislikes. The mic connects to the main radio not the control head. I think that's a plus. It means there are a number of head placements that wouldn't be possible otherwise. Such as on the sun visor, above the mirror. I don't like dangling cords.
The operator's manual is downloadable from Kenwoods site. I'd recommend doing so and taking a look at the options/features/controls.
Kenwood's programming scheme is easier for me to understand than any of the other manufacturer's. that's another one of those 'preference' thingys, YMMV.
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What, exactly, is a 'noisy' receiver? I don't understand that description. The more sensitive a receiver the more 'noise' it will receive. So, roll that RF gain back, or use the attenuator? Will you 'loose' some weak stations? Sure. But if the noise is louder than they are, you didn't 'have' them to start with. Just really don't like the normal 'pops', 'scratchy' atmospheric stuff, that sort of thingy? Sorry Charley, that's normal with SSB. There is a squelch control, BTW.
Is the TS-480XXX the best thing in the world? Nope, but it's a dam close runner up.
- 'Doc
Absolute best way of finding out if you'd like it is to get your hands on one and operate it. Yeah, right, easier said than done.