1/2d6 vs. 1d6-1 in DC Quick Reference

[Vassily]

I'm sure that I haven't found the right place in the text yet, but is there a guideline to help decide which one to use? Sure, the intermediate damage class steps may not come up too often, and I'm no mathematician to work out the results spread between the two, but I seems that the choice may be mostly cosmetic. If so, who makes the choice, the GM for the campaign as a whole, or the PC for the power use?

[Steve Long]

Generally speaking you should always use the half-die number, not the die -1 number, but the final decision's up to the GM.