Does reading a bad class ever really piss you off? It upsets me a lot.
In what Tier would you put the Soulborn from Magic of Incarnum? I looked through the first post and I didn't see it. I think it's Tier 5, but have less optimization skill than many on these boards.
As for why I think it's Tier 5:
Due to their extremely limited meldshaping ability and barren class features, the Soulborn fits no role they don't choose and they must specialize a lot to fill that role even marginally well.
It has a single unique alignment-specific class feature of limited power, Incarnum Defense, the benefits of which are widely available from other sources. Almost all of those other sources are easier investments than two class levels (The level at which Soulborns acquire Incarnum Defense).
To appear fighter-like, the Soulborn gains a pathetic three bonus feats from a limited list.
The Soulborn is barely worthy of being considered a meldshaping class, since it must wait for FOURTH LEVEL before it can shape any soulmelds at all. Any other character who takes the Shape Soulmeld feat can shape soulmelds earlier, and in fact the Soulborn must wait even LONGER (6th level) to even get any essentia!
Also the Soulborn only has half of its soulborn levels count towards meldshaper level. What a slap in the face!
In addition to the above, the Soulborn gets very few unique soulmelds. In fact, you can get the Soulborn-exclusive soulmelds before the Soulborn with the Shape Soulmeld feat. If ever there was a class that needed a doctor, this is it.
Of the five Soulborn-exclusive Soulmelds I counted (Fearsome Mask, Gloves of the Poisoned Soul, Mauling Gauntlets, Soulspeaker Circlet, and Thunderstep Boots), maybe 2 out of 5 are worth anything. The best ones might be worth the feats to use them but they're definitely not worth the four Soulborn levels to use.
Fearsome Mask: A good intimidate-booster that is probably easily replaced (It gives an insight bonus). The gaze attack would be good, but there are a few hiccups named SR, fear, mind-affecting, and will save. IF your enemy is vulnerable to fear and mind-affecting while also possessing no SR (remember the Soulborn uses half their levels for meldshaper level, so you're never overoming anyone's SR) and an abysmal will save then MAYBE you'll scare them.
Gloves of the Poisoned Soul: These give you a pretty good poison. Too bad it allows a save, thereby depleting a lot of its use.
Mauling Gauntlets: These are actually pretty good. Don't think about the hands bind, it'll just piss you off (If you are binding it to your hands then you probably have Improved Unarmed Strike. The hands bind... gives you Improved Unarmed Strike. The damage bonus is nice though.)
Soulspeaker Circlet: The throat bind gives you telepathy without calling it telepathy, so an ass GM could deny you, but if they don't there's your ticket to Mindsight. Largely utility, I like that this soulmeld basically allows you to change your languages known from day-to-day. The problem is that you need the Crown bind to speak the languages. It's also pretty wonky that the throat bind gives you telepathy and the crown bind gives you the ability to speak languages, because it seems like they should be vice versa. Perhaps this is further proof that whoever made the class was a stoned asshole.
Thunderstep Boots: A wee bit of additional sonic damage on a charge. If you invested a lot into this soulmeld you might be doing an additional 7d4 - on a charge - at level 20. Get pounce and it might add up, but if you don't have pounce don't even think about it, ever. If you bind it to your feat you can stun someone - if they fail a fortitude save - if they're vulnerable to stunning.
Oh and they also get smite. Since they don't get it at will, it doesn't save the class. The 20th level capstone is a fifth smite per day.