Talisman of Resurgence

First of all, I tend to use a very simple calculation to turn a given mana PPM into Mp5. Any mana return happening every minute is included, and Divine Plea is exactly like this. 60/5 = 12. So simply divide the mana PPM by 12 and you'll have it on an exact Mp5 value.Secondly, Paladins need to clearly include their stat buffs (or spell it out if they aren't).
We have Divine Intellect (2%/4%/6%/8%/10% talents, all five traditionally used) along with Kings (10%), making up a full 20% buff to any and all Intellect we have. So if we multiply it by 1.2 we instantly figure out the actual total Intellect an item gives to Paladins and this would always be calculated first and be kept in mind.
For example, a 20 Intellect gem "is" actually a 24 Intellect gem.These easy numbers will make it more natural for you to know what you're actually getting and also not to do the same mistakes again.
Therefore, this trinket's passive Intellect is worth in an average boss fight:

153.6 Intellect
2304 mana
68.736 Mp5
0.93% Crit (Illumination regen for this not included above)
30.72 Spellpower128 Intellect on this trinket ammounts to 153.6 Intellect which is 2304 mana (1 Int = 15 mana). Divine Plea restores 25% (*0.25) or 1/4 (/4) of that every minute, so 2304 / 4 / 12 = 48 Mp5. 1% Crit takes "around" 166 Intellect each, meaning "around" 0.93 Crit. You could also add how much average mana return you expect from your crits for that ammount, however it involves more intricate calculations involving for example how much Crit you're already stacking.Replenishment is essentially 1% of your mana pool as Mp5 and it should be up nearly always, however you may want to calculate it as 90% due to change of targets, movement and other oddities in fights. 2304 * 0.009 = 20.736 Mp5As for Spellpower, 153.6 Intellect gives, with Holy Guidance (4%/8%/12%/16%/20% talents), 30.72.
You can use the trinket's effect when casting Divine Plea every other minute (just like you would with Avenging Wrath) so as to be able to heal for more during the duration even as you keep regening a good chunk of mana.I might also add that the debate over the usefulness of Spellpower for Paladins as of 3.2.2 is essentially about how much you prefer and are able to successfully keep using FoL as your main heal, maxing out its performance.
At a higher gear level, buffing FoL rather than simply your Intellect is actually a very good alternative to the spending of HL's hefty mana cost and its overhealing (even if it all gets transferred to the beaconed target now, it also mostly overheals him too).
We actually have been offered very good new tools to do this, like the HoT from SS. It should also be noted both of these spells have high coefficients with SP, namely 100% for FoL and 75% on SS.