As for gear, it favours warrior gear (But you will still want a teenie bit of spelldamage here and there to bump up your consecrate power and I think Holy Shield benefits from it too) - Seal of Blood does damage proportional to your white damage - And while it does not do increased damage when you crit, the seal itself is capable of critting independant of your (WoW Gold)main attack and it does increased damage from, for example, a windfury proc that gives your extra swing increased attack power. 

You scale with strength more and your gear will almost 100% resemble that of a warrior. Numerous advantages include ability to tank with low spelldamage gear and the ability to choose any one-handed weapon you want. Downside is that one-handed weapon needs a decent DPS and you won't generate as much threat as a SoRighteousness/JoCrusader spammer with 300 spelldamage, but you'll have more(WoW Gold) damage mitigation and you out-aggro the DPS as it is anyway.

As for my threat per second calculation, over 10 seconds of combat...

Consecrate Rank 6 for 74: (74*10) = 740 holy damage over 10 seconds.
Holy Shield for 159: ((159*4)*135%) = 858 holy threat (Holy Shield generates 35% extra threat) over 4 blocks over 10 seconds.
Blessing of Sanctuary for 46: (46*4) = 184 holy damage over 4 blocks over 10 seconds.
Seal of Blood for 65-85 with weapon speed 1.6 = (6.25*((65+85)/2)) = 468.75 holy damage over 10 seconds
Judgment of Blood for 415-440 with 1.25 Judgments per 10 second span = (1.25*((415+440)/2)) = 634 holy damage over 10 seconds.

Total: 2884.75 Holy Damage (Increased threat from Holy Shield included) over 10 seconds.
Threat Generated purely by holy damage: (2884.75)*190% = 5481 Holy Threat over 10 seconds, averaging at (WoW Gold)approximately 548.1 Threat Per Second purely from holy damage alone.

Judgement of Wisdom procs for 37, I will assume a 50% chance to proc Judgement of Wisdom with any attack: 6.25 auto-attacks, 3.125 proc wisdom. 6.25 seal of blood procs, 3.125 proc wisdom. 1.25 judgments, 0.625 proc wisdom = 254 additional threat over 10 seconds.