Shmuckumpoo
Grandfathered
Full +healing only makes sense if you're using max rank. That is the only thing it beats int / stam stack at.
A 2600 hp / 2800 mana / 130 healing power paladin spamming r3 FoL will have higher healing throughput than a 1900 hp / 2000 mana / 240 healing power paladin spamming r1 FoL.
Its actually +334 healing (if I include WSG rings and enchants) vs +137. So quite a drastic difference. Now let's take a deeper dive into the calcs.
spell coefficient for flash of light is 42.85% irregardless of rank.
+137 healing: 137*42.85%=58.7
+334 healing: 334*42.85%=143.1
So 58.7 vs 143.1. These values are the actuals added to each flash of light cast. Now lets add them to the top end of each flash of light. 77 and 171 respectively.
+137: 171+58.7=229.7
+334: 77+143.1=220.11
So looking at this it shows that yes. using r3 at +137 healing does heal more than r1 at +334 by a slight margin of 9. But this does not take into consideration mana spend.
+137: 229.7/70=3.28
+334: 220.11/35=6.29
3.28/6.29=52%
Here I show that per single point of mana +334 gives you more effective healing at 6.29 per 1 mana whereas +137 only nets you 3.28 per 1 mana. A 52% net increase. So putting this into a simulated real world scenario. Assuming the paladin is only spamming flash of light (happens a good bit actually). The paladin with +137 will oom at about the same time the +334 paladin is sitting at 50% mana pool.
Now yes this does not consider hp lost by stacking so much health. This is the obvious trade-off and is scenario driven as I stated earlier.