Before I begin, very nice guide. I've used it to help gear both my DK and plan to gear my mage.
Anyway, I wanted to check my logic on a few things regarding my DK with others.
1. Some people swear by Dual Wielding and at 85, I can see the reason why (Mastery, AoK trink, HB-NS-FS rotation) but at 70 it seems like the rotation/burst is similar for DW/2H Frost DKs. I've found that when using a 2H my RoFC procs tend to take a bit longer, but I also always have more runic power and can play a bit more offensively, as I will usually have enough runic power to Death Pact or LB - Death Coil in bad situations. When Dual Wielding, I start out w/ a cap of 100 runic power instead of 130. I also generate a bit less due to not having MotFW talent. I'm having some trouble choosing which is better, as I can see DW's burst being better in certain situations.
TL;DR: Do you prefer DW or 2H as a Frost DK?
2. My DK is Human, and I therefore have space for 2 trinkets. I made this toon recently however so I don't have access to any of the better (60-120) stat Battlemaster's trinkets. Currently I'm using the Sonic Booster + Gnomish Lightning Generator. Sonic Booster is definitely a favorite of mine, even w/ Stamina being less valuable compared to resilience, it's still worth something, and the proc is great. The second slot I can either use my JC crafted Shadowsong Panther (similar to Beserker's Call) or the GLG. The problem with using the Panther is that It doesn't really line up with my burst. This is due to me having the Synapse Springs. After 10s of PoF, I can pop the trinket, but at that point it's usually more beneficial for me to hit someone w/ a 1-2k lightning charge rather than get a 320 ap buff especially if they're close to dead and or I'm out of runes. The only real drawback from GLG is the fact that maybe 1/10 times itll hit you as well.
TL;DR: Gnomish Lightning Generator [81 crit, 1-2k dmg [60s CD]] vs. Figurine Shadowsong Panther [80 ap, 320 ap on use [15s duration, 90s CD]]?
Note: As far as trinkets go, I'm not against the Blackened Naaru Silver from Sunwell, I just haven't had that, Apolyon, Felfury or the BP Grips drop yet.
Beyond those two questions, there isn't much else that pops to mind. I will share a few of my experiences with other though.
When it comes to 70 twinking as a DK, you're definitely going to want two or three different sets of gear. One will be an arena set, stacked with resilience in almost every gem slot. We have enough burst as it is, we really don't need much more through gemming, we're much better off getting our resilience above 500 so that we aren't one shot by rogues and mages in arena. Your second set on gear should be a set with full strength gems. Use this in random bg's and whenever you're in a RBG where you're a EFC killer. The amount of damage that Frost DK's can put out is insane, you can easily down an EFC if they're caught off guard in even the slightest regard. Last but not least, get a set of gear that has a lot of stamina and resilience in it. Use this when you're speced blood and running flags. In this regard, resilience will always outserve you compared to Stamina. You simply need enough stamina to live through an initial burst from the enemies trying to take you down. Beyond that, you're either going to be healing yourself or have someone healing you, and resilience will allow this to happen. If you can hit 500 resilience you'll have ~32% damage reduction base. Add to that your dmg reduction from Blood Presence, Bladed Barrier, IBF, AMS, etc and you become damn hard to kill.
