Now vanquishes are usually very easy, so I figured I'd screw running two Monks and just bring one. Why not? I even brought along a dual Fall Back Paragon for extra mobility since I was planning on cartographing as well as vanquishing. The build seared its way through all the remaining vanquishes I attempted, including areas in the Desolation, Vabbi and Istan.
After that I began to wonder if I was indeed running too much defense in other areas of PvE. When I PuG for example and find myself running ER, I know for a fact that I usually wand more often than cast. I'm almost never under pressure, and all that prodigious defense is overkill. Question is can a healer henchman do the same? It turns out that they can. I tried the build in increasingly tough areas, going through Borguus Blisterbark HM, Raven's Point HM, Rragar's HM, Frostmaw's HM and now Duncan HM - all with fairly little problems.
Here's a screenshot of the Duncan run I just did. I apologize for using the glitch, but then it's the only way to get into Duncan without re-doing the four bosses:
Some Q&A's: I have Heart of Shadow because it's an integral part of the glitch. I'm running 16 Energy Storage because I recently changed my Energy Storage helm to Superior runes for easier ER. I have an Air Wand and Focus because I don't have a 40/40 Energy Storage set, so my 40/20/20 ER Enchanting set will have to do. I'm running Blessed Insignias without an enchantment because I only have one set of armour, and most of the time I do have enchantments.
I wiped once in the dungeon - that was approaching the many Restless Dead spawns just before the Stone Summit Rangerspike group (the third room). The spirits I left behind aggro'ed the patrolling Stone Summit mob I could usually avoid, which is my mistake, and the Summit rushed me while I was fighting the Restless Dead popups. Resulting fight was still pretty close. The team had been fighting ~4 consecutive popups of Restless Dead and the Stone Summit approached from the back with about 5 Restless Dead still alive, but even though I wiped by that time only ~4 Stone Summit and ~1 Restless Dead was still standing, and Razah escaped without dying. The other time I died was near the end when I forgot to micro Prot Spirit before I swapped spirits

Grand total of times I micro'ed Prot Spirit and Aegis before I got to Duncan: zero - but I did micro the spirits a lot.
From this I'm pretty much concluding that I'll never step into another PvE area with more than one dedicated healer. It is simply not needed. Party heals are very helpful though, especially Kaolai because heroes are so fast with it. Henchmen healers don't have party healing and if unprepared (or lazy) it's pretty often that AoE does massive damage to the party, so this shores up a weak point.
Comments, suggestions for my build, etc welcome.
PS: Yeah my build sucks. Pity it needs Heart of Shadow and Swap, and if it does I don't have the room for spells like Lightning Orb.
PPS: In case anyone wonders how I killed the Stone Summit mobs en route to Duncan, here's a screenshot of the first mob. I forgot to take it until we'd already engaged, but the heroes were flagged and spirits were all down before aggro.