The problem now is that any rally will have low volume until certain thresholds are passed and people feel safe buying in again. During that time, any work can be undone overnight by a dumper/manipulator. So it's a wasted investment at this stage.
The best metric for me would be a map of the largest holders of BTC -- I know this is impossible, but we can at least track the BTC/address density. Once can assume if this is decreasing then there are less whales / dumpers, all other things being equal.
Look up bitcoin days destroyed.
