The Icom 706 Mk II G is a decent mobile with much better DSP. You just need a PhD to be able to figure out how to operate it.
Interesting point. There are indeed complaints about the sound quality of the FT-897D; personally, I think it sounds great.
I'll concede that the 706mkiig is potentially the single most popular HF/VHF/UHF all-mode radio. It got that way for being a very solid performer both mobile (in a car) and sitting on your desk. If I were to install a transceiver in my car, the 706mkiig is the one I'd go with.
However, there are hams that have studied the relative power usage of the 706mkiig and the FT-897 and found that the 706mkiig tends to suck down quite a bit of power even while only receiving, making it a poor candidate for portable (extra-vehicular, shall we say?) activity, such as mountain topping:
The FT-897 can be configured to use minimal current on RX by turning the dial light to automatic, and disabling the DSP. Using headphones helps as well. In this mode, you can get down to 550-600mA, which is much lower than counterparts like the IC-706. In fact, other than the dedicated manpacks like the F-817, VX-1210 and military equivilants, only a few rigs like the Elecraft are more frugal.
Just looking at the specifications for the FT-897D and for the IC-706mkiig:
FT-897D:
Squelched: 600 mA (Approx.)
Receive: 1 A
IC-706MKIIG:
Rx Standby: 1.8A
Max Audio: 2.0 A
I don't know what the OP means by mountain topping -- does he mean he's going to drive his truck to a mountain top and transmit from there or does he mean to toss everything he needs in a backpack and hoof it to a high point? The radio he chooses depends on that distinction. If he's backpacking, I would say the FT-897d is the best choice of the two.