If you are seeing it track up as much as it is track down, then it's probably staying pretty consistent. Tracking never stops, it's always tracking. The speed changes how long it will take to get to the new ground level. If you have slowly changing ground, setting your track speed slower would keep it more stable. If you have ground that's changing all over the place, set it up for a faster speed. If you are wondering if the tracking is doing its job go into pinpoint. Raise and lower the coil and if you don't hear much audio change, then it's probably just fine. If you are hearing too much audio change you probably need to adjust your speed. The tracking was intentionally sped it up as people complained that the DFX was too slow. Tracking does not use the filters so setting them will not affect how it tracks. It is triggered off of changes in the ground. The faster you swing your loop, the higher the filter you want to use. Yes, in difficult ground it is good to lock the track to your manually balanced setting. Everything to which the V3 responds (with sufficient strength), generates a VDI number. The ground mineralization is no exception. When the V3 is ground-balanced properly, the V3 sniffs out the grounds VDI number and sets the circuitry to lose sensitivity to targets with that VDI number. All we have control of is how fast or slow it takes to get to that balance point.
The tracking on the V3i has tighter limits to try to get it to zone in to where it needs be and not to have such a large offset when done balancing. It's slower, maybe that's why some people have reported it