Regarding BT between NXTs, I've used it a lot on several projects. It does work for
me. With one limitation, I find it to be reliable. That limitation is connecting
multiple NXTs, in an area with dozens (hundreds) of people with cell phones. There is
just too much Blue tooth activity. This past New Year's eve, I demoed my robots at
an event in a large auditorium, with all kinds of electric equipment, electronics, music,
and lighting equipment, and 100s of persons, probably most with cell phones. When
I started a duet dance routine, the master always connected to the 2nd dancer. When
I tried to connect 4 robots for a dance routine, usually BT connection failed to one of the
three support dancers. In my house, connecting 4 robots is very reliable. There are some
limitations, as to how fast you can send large amounts of data. I view designing how much
data to send when, as just part of the robot design process. I use NXC for my projects and
have got many good BT ideas from Benedettelli' book, Creating Cool Mindstorms NXT Robots.
For NXT-G, there are some good ideas at <http://www.nxtprograms.com/>. See the
project Steering Remote Control for a project using BT.