After playing a bit on PoTD with various builds including some of yours I would recommend to NOT dump attacking stats in favor of Constitution unless for veryveryveryvery specific build. Having ~20 extra deflection does matter but
you see, when you dump STR for some extra hp what you really do is keeping generally same +fortitude (because -str +con) while trading your ability to do amage AND possibly sucking at some unique abilities class or race has. And since as a tank you still better to have high accuracy to land disabling abilities (my monk uses rapier with 3 bonuses to hit), you can also do crits, which helps somewhat with doing damage. If you completely dump Might though you do almost no damage in combat and it often can lead to funny situations when your DPS guys are down but you can't kill the enemy
Same about some other stats, for example Int, may seem good idea to dump on some characters but then duration of your disablers or range of your auras become crap; but pumping it too much also does not affect combat in critical way for some classes.
So for a MonkTank for example, maxing Per&Res is a good idea, lots of points in Int is also good, but dumping Str I wouldn't go that far, and also dumping Dex isn't the best option. Why? Well, because he often accumulates wounds faster than he can use his abilities and in heavy armor sometimes you have to wait too long to land that flying kick.
I'm thinking on respeccing into something like Per+Resolve, some int (although I think it is arguable if you actually REALLY need those 3.5 extra seconds for FoA instead of 40% (!) damage in combat - just think what we're actually paying here), moderate stats everywhere else. Oh and Moon Godlike is best especially if you have no cleric in party. Non-dumped STR helps with that too. Also Torment's Reach when you look it is kinda crap, you might get more by using faster attack rate combined with some unique weapon that has status effect like prone on crit (we're stacking accuracy anyway).
I wouldn't dump Dex for Chanter too unless you're total tank, since you can stack spellbinding items and scrolls on him and constantly cast spells in combat while chanting and then also use incantation.
tl;dr all-or-nothing builds may not overperform regulars more while paying a way too high price for being so specialised.