I would keep in mind, I haven't run the math for awhile, but since Icy Touch doesn't scale from weapon damage, there is a point where your regular abilitys will generate more threat, and obviously a lot more dps with a better weapon. My Heart strikes seem to generate at least as much threat with my 264 2 hander as an Icy Touch.
This point is not attainable in this expansion, and likely not in the next.
Assume IT hits for 1000; a fairly conservative figure. IT base threat = 7x damage, for 7000 threat. Frost Presence then applies, for a 2.04 multiplier, leaving a total of 14,280 threat. HS would, of course, need to hit harder than 7000 damage after armor modification to exceed this figure.
Now, let's assume 7000 AP. This is likely to be too high for tank gear, but who knows, I haven't looked at mine buffed. It's ballpark, and would give you a 1076 average IT assuming Imp. IT, which unless someone else is providing Imp. TC you take. Assume also a heroic Ramaladni's, a 294.7 DPS weapon, 3.5 speed, 825-1238 damage. Crit rate, etc are left aside for the moment; we just want hits right now.
HS is 50% weapon damage, modified by Bloody Strikes for +45% damage, make that 69%.
Average weapon damage from the axe is 1031.5, round up to 1032. 69% of this is 712. Instants follow the equation normalized_damage = base_weapon_damage + (X * Attack Power / 14), where X is a weapon-type-dependent value, in this case 3.3 for a 2her. Substituting in gives us:
normalized_damage = 712 + (3.3 * 7000 /14)
Which we can then proceed to solve for:
normalized_damage = 712 + (1650)
and then of course
normalised damage = 2362.
Thus, the average HS hit with a heroic Ramaladni's at 7000 AP is, pre-armor, 2362 points of damage. Add 20% for a 2-disease strike, and you have 2834. It is safe to say that we have a full stack of Dark Conviction, so adding a further 9% to that gives us 3089 damage, rounded up. With the 2.04 modifier from Frost Presence, we have a total of 6301 threat, assuming a 0-armor target.
So to say it again:
IT threat: 14,280.
HS threat: 6301.
There is simply no comparison.