I rarely if ever play quests on elite, it's basically only raid that I play on elite. And on elite, harry / sally for example hit's so high ac, that no ac build can take it (more or less), I've "dps-tanked" vod with 406 hp, (not maxed, con, shroud item, no madstone / rage, etc.) And I easily took aggro off barbs and soaked him.
You US-players really really overestimate hp and underestimate <400 hp. Seriously, any cleric / caster can keep a player with 350+ hp alive, hell, I've been in shroud elite as melee with 300 hp and I stood up to him (no ac to mention). So no, 500+ hp doesn't get chewed down too fast.
His stun / trip dc will be that of a FB since he will have almost the same str (50-52, fb at 56-58). (dc, 10+20+2(kensai)+10item) = 32 without item, 42 with item, 43 with max str. VS FB, 33-34 / 43-44). Trust me, it's enough, and if it's not, then this build wont take stunning blow and instead take something else, like luck of heroes or something.
Ofcourse it's not that uber in mod 8, it's not until mod 9 it really shines, when it gets
+4 damage
+10 strength (+4 tome, +1 levels +8 ps)
+4 seeker
+1 maxed pa
+3 boosts
+5% more attackspeed on boosts
+9 to hit
So I can understand if you don't think the dps is totally uber at the moment, but fact remains.
((Check back a few pages and you'll see the enhancements planned for mod 9, or check the post on the EU forums where I have done em in detail)).
The "Weaknesses"
Ofcourse this build has weaknesses, but no major ones, since it will serve it's purpose and still have ac enough for normal, hard, and some elite content, evasion and good saves. So the only weakness considering it's a maxed dps character is that it lacks the Teir III enhancements which could be great in future modules. Every build has weaknesses but some are so obvious that you really don't have to point them out, for example if you make a pure caster you don't have to type "weak melee dps".
So, the ac is enough for normal/hard/some elite, the saves are enough for normal-elite, the hp is enough when the ac doesn't do anything. Hence, it doesn't really have any weaknesses. Only moderate ac is ofcourse a "weakness" , but would you go for more ac you would sacrifice more dps, and thus "not maxed dps" would be a weakness, it's all about balancing it out. And no, this build isn't really the best in all situations, but it's **** fun to play and it's best in some situations. (eg when you only need dps)