My friend has this exact phone, and we took it on a backpacking trip 3 weekends ago to the Red River Gorge. It's a 3+ hour drive, so on the way down I beamed him the Palantir application (I had to use Filez to beam both the app and the data) and then he could control my Empeg with his phone. That phone is the nicest phone/pda combo I've seen, and you are right when you say that the sound quality is very good. I used his phone to call my wife a few times, and it was crystal clear, even in the hills of Kentucky.

I think that you'll do ok with the 16M of memory, most palm applications are very very small, it's the data that might eat up your space. Mapopolis maps are usually about 1M and in Ohio where I live they are split by county, so you could probably only store a few counties on there.