Bounus armor rocks IMHO there is no real choice - tier gloves or Kraken You have Icy Touch, threat is not an issue for DK's these days. I was up to 30k tps and 24k sustained spamming IT,on Surfang the other day - drove my pally tank partner crazy.
Personally I have the 4 piece tier (but the legs are 251); I have the Gloves of the Kraken and I have a set where I use the 2 piece bonus. (gloves/helm) I acutally like the extra cooldown on the tier; it's fun to play with. However, for bosses I tend to use the Gauntlets of the Kraken and for trash I use the tier gloves/helm for the extra DnD damage. Frankly, I think the tier gloves with bonus armor are fine; you don't really need to waste the emblems on the Kraken; you have to decide if the extra couple hundred HP is worth the emblems.