QUOTE (Yerameyahu @ Sep 13 2010, 09:44 AM)

Off-topic: that really should be how grenades are targeted anyway. Someone's ability to wiggle isn't relevant for an explosion, and letting them dodge the attack really screws the already screwy scatter rules.

Grenades are always a tricky thing to model, since it's an attack on the area you occupy, not on you per se, so defense works differently than with sword swings or bullets or Powerballs.
I look at ranged defense this way: in combat, everyone is constantly dipping, weaving and positioning to present the least possible target area; a skilled/trained/nimble combatant will be better at the split-second reactions this requires to avoid firearm and projectile attacks. This is represented by your base Reaction normally, and a Full Defense action means you're focusing on this, concentrating more on your posture, positioning and direction instead of attacking or doing anything else, so you add your Dodge skill. (Gymnastics dodge is jumping/flipping around for a more cinematic version of the same thing, natch.)
None of that has anything to do with a small object falling at your feet and filling the area with shrapnel; at the very most you could angle your body to take most of the hit on armor, but "dodging" an explosion generally involves *being somewhere else* when it goes off. Some of this is handled by the timer and giving a chance for people to make move actions; a wired-up sammy could have enough actions to drop his gun, pick up the grenade, and toss it back before it explodes, but it's not satisfying to most players if there's *no* involvement on their part (probably why RAW allows an opposing dodge roll).
How I resolve it is reusing the game's scatter mechanic; if the grenade is targeted straight at a character or their space, and the unopposed attack roll would place it there with 1 m or less scatter (ie, the grenade actually reaches their space that character rolls their Reaction (plus Unarmed or Melee skill on full defense) against the opponent's original attack roll; any net hits are expressed in meters of scatter away from the targeted character, rolled seperately on the scatter table. So, the targeted character hit the grenade with a kick or knocked it with their gun-butt or something, and it's a bit further away, giving them some survivability, but it's more realistic than somehow one's dodge ability making a grenade magically bounce back into the opponent's face when by scatter rules it shouldn't have come near the target in the first place.
I don't like giving extra movement to characters when it's not their turns; it makes things messy. For most grenades you have a couple of seconds to try to move before the attacker's initiative pass comes back up, of course with airbursts you rarely get the opportunity to defend at all.
All this tends to make grenades a bit more lethal, especially with liberal use of the Chunky Salsa blast-channeling rules. Moral of the story? Know the terrain, use cover, don't get out in the open! Works well against both 'nades and Fireballs.