I have had the fewest problems and the best/most consistent results using firmware 2.80 and chipset 2.50. I tried 3.0/2.80 when that combination first came out. The combination would probably be my second choice, but the track logs were not as crisp. With the recent release of chipset 2.90, I tried again (firmware 3.0/chipset 2.90) and the resulting track log was awful!
The following screen shot tells the whole story. The pink line is the route that I actually walked. The yellow line is the track log. I walked in the clockwise direction. Note that the track log was ok for a few blocks. Then it went off and stayed off and by quite a bit.
