I have both the '710 and the '71A, and haven't heard about that 'clicking' thingy, neither of mine does that. I don't use a mic extension with the '710 in the house, but do with the '71A in the car. That extension really isn't necessary, but it's bot difficult at all. I made my own from parts from Wal-Mart. A phone cord and double-female connector from the telephone department works just dandy (right number of contacts/conductors). That 'under the seat' worked out fine for my car. Or, leave the 'head' connected to the 'body' of the radio and just mount it as you'd like. The 'body' of the '710 and '71A are the same, shaped a little differently, but the same radio. If you don't think you need a TNC then the '71A is definitely cheaper. The heads for both radios are interchangeable, both work just fine. The TNC is in the head of the '710.
If you get either new then there's no outstanding problems with either. The older ones did have filter failure problems, but Kenwood fixed those problems for free (except for shipping).
As for the mic connecting to the body rather than the radio's control head, I think that's a 'plus' in my case. There's only one cable to run, and the head can be mounted where ever you want to put it (above the visor, the roof, etc, with no mic cord dangling from it. I put the head on the dash just to the right of the instruments in the last two vehicles I had it mounted in. Glare is/was a little bit of a problem but i 'cured' that with a home-made visor over the control head's face.
Best I can advise about them is to sit in front of both, see if either 'fits' your particular circumstances. If either doesn't 'fit' you circumstances then I'd say look for something else.
- 'Doc
The '71a's in the car because I don't have need of a TNC in the car. I do APRS but differently than with the radio. The '710 does that APRS just fine, but I prefer a laptop's screen to the one on the '710, bigger/easier to see.
The most aggravating thing with either radio is that I had to mark the knob's so that I could see them, white paint on the 'index' marks on the knobs. Oh that was just terrible!