Havrik Stoneskimmer
Adventurer
I don't think I would play it that way at my table, because it diminishes powers that trigger on a hit rather than an attack. Even in cases where the player knows they've been hit, I wouldn't tell them the damage and let them decide whether to be hit or not - with the possible exception of powers that are flavored to actually rewind time or predict and avoid the future, etc. In that case there's a narrative reason for the PC to be able to decide based on the projected damage whether or not to use the power.The part that sees some table variation, is when exactly do you use the power... In some groups, you have to declare you're using an interrupt the moment someone decides to attack you. In some groups, you wait to hear if they hit you and by how much. In some groups you also get to hear how much damage they do and what conditions they inflict before using the interrupt. I'm in the last camp. When I DM, I rattle off everything at the same time, "31 vs AC, take 28 poison damage, you're slowed and taking ongoing 10 poison damage, save ends both, don't forget you're in his gas aura and have vulnerable 5 poison on top of that." Then the sorcerer says "no thank you, immediate interrupt, I pop Sudden Scales putting me at AC 33, and that misses."
I do however let players ask "would a 22 hit?" before using Heroic Effort or similar powers that give a static boost to a roll, so as not to waste a power when it doesn't make a difference. Not sure if that's strictly by the book or not.