Tasting it will not be an issue - even drinking a few glasses.
The problem with drinking a lot of RODI
water is that it will leak transmembrane soluble nutrients from your cells, and because insoluble nutrients stay in the cell water could rush into the cells at such an amount that it could cause lysis (cell bursting). Cells in the human body want to remain in osmotic equilibrium. So if you keep drinking too pure of water it could cause some damage. But you would need to drink quite a bit.
This is a similar reason as to why we need to slowly acclimate inverts. They are not a biologically sophisticated, and lack some of the safe guards that most vertebrates have. Rapid changes in salt concentration can be even more detrimental to them.
Much less salinity in your tank - there cells can burst with influx of water.
Much more salinity in your tank - they could shrink and shrivel.