In general, it's a good idea to used signed ints whenever possible.

Here are the only 2 reasons I see for unsigned ints:
- matching hardware or wire spec
- You need the extra range afforded, and don't need negative numbers.

And the reasons for using signed integers otherwise:
- It prevents other overflow and comparison problems. Ie, fixes other dumb coding issues like "if (my_gold - your_gold > 0)" becomes a bug when the gold types are unsigned.

The Bluetooth 3.0 + HS spec does exactly what you mentioned -- it takes the Bluetooth profiles, and runs them on top of WiFi.