Of course it depends on what you're doing with the information. If you're compressing it in order to sort 100 million board positions for a minmax algorithm, it might make sense to use a representation that makes queries cheaper at the cost of size.

If instead you're trying to store every competition chess game in history, then it depends on what you're trying to do with them. Look for similar board positions?

If you're trying to allow inmates in a Dumas-inspired prison secretly play chess against each other over a covert channel, then detection is the problem. Which might mean compression (fewer signals to hear) or masking the signal as random noise.