Need some WHM Speedrunning tips please

[Spoekes]

When I identify that they're not continuing their pull (no more nearby monsters or theres a road block), I use Presence of Mind (my preference of the two buffs.... *shields face, since the rest of the thread seems to use Divine first*)
-Spam Cure II + SoS for enmity/MP
-Regen when they're -completely- topped off by a cure and I -think- they can withstand a few hits for the GCD (so in other words, not right away)

Let me try to explain you why, in theory, it is better to use Divine Seal first:
If you use Presence of Mind, you cast 20% faster. This increases healing by a flat 20% and also increases your mana usage by 20%.
If you use Shroud like you mentioned, you burn it away quickly and your aggro at that moment will half, but you are spamming cure 2 with 20% more speed. Its better to use shroud at roughly 70% and once you really built some amount of aggro worth reducing.

Divine Seal on the other hand increases heal for a flat 30%. Without increasing mana cost.
Divined Seal'ed Regen ticks really strong, thats why it pay off casting with DS. Medica II will even more increase the heal over time ticks, so you buy yourself time to either holy spam or regen mana and or use cure instead of cure II.

[Saseal]

Let me try to explain you why, in theory, it is better to use Divine Seal first:.

Okay, yeah - I see what you're saying - I'll try it the next time I end up in a speed run - and hopefully turn for a better strat.
I think my method of thinking just got burned into me too early by (possibly undergeared?) tanks that barely survived one cast of cure x_x (when I first encountered speed runs)