So, I'm heavily considering another avenue, based on Robby's Warlock fix, rather than basing it off of the Barbarian fix. We've already got a melee combatant in the Totem Rager, as it is. Besides, if the build is going to figure heavily on blasting and eldritch glaive later in levels anyway, I may as well embrace it.
The Hf Warlock, Binder, and Legacy Champion levels are pretty much set. No need to change them, really.
(Blurg, Wall of Text)
[spoiler]Now, if I keep the Warlock fix on the multiclassing side of the gestalt, I'll still get 18/20 levels of eldritch blast and invocations. This will bring the total blast to 34d6 at 20th level. If, on the other hand, I make it the secondary class, going Warlock 20, the Hf blast will be 36d6, I'll get two more invocations, and up to the full 10/cold iron DR, not to mention the very nice Imbue Item feature. Then there's 11 levels open on the other side, but advancing Hellfire Warlock as normal and through LC has slightly less pay-off, since Warlock levels would already be at full progression. I wouldn't, for instance, get at a particular level double the eldritch blast and invocations, but it would still advance the hellfire blast damage, which is really the main point to begin with, so not a complete waste. However, that does mess with BAB progression, or at least make it messier, among other things.
On the other side, I originally considered going with Rogue, for a few semi-decent class features and Sneak Attack. It makes for a very nice skillmonkey, too, but ends up being squishy and spreading those delicious skill points out among everything I need made things less than amazing.
Hexblade seemed like a pretty synergistic class, as it's heavily based on Charisma as well. But the class as it is just isn't worth it, and doesn't get me the skill points I want; any fixes to the class would bump it up a tier and make the whole point moot.
Scout is nice, though, as it gets a good amount of skills, skirmish damage, a couple bonus feats, fast movement, etc. Save this idea.
Ranger is also nice, getting the same HD as scout, though fewer skills. It does, however, get spellcasting, but I can't afford to put the points in Wisdom without getting MAD. I could at least get an item to boost Wis, if need-be, and just focus on buffs that don't rely on wis mod. The combat style trees don't help me at all (Improved Precise Shot at combat mastery is nice, but everything else in the archery line is worthless toward Eldritch Blast; Two-Weapon Fighting won't help, unless I wanted to qualify for the Dual Wand Wielder feat.) Too bad there's only one option for switching out the combat style for something else, and it's banned from this game, besides being a tier higher (shapeshift variant ranger). The options for getting rid of spellcasting aren't really worth being less MAD, since Spell-less ranger from CW is pretty gimpy, and the one from CC would be decent, as there are a couple ok feat I might want anyway, but doesn't really size up to spellcasting, plus I'd still have to use UMD to cast spells from the list (not a problem, but still an annoyance).
Still, full BAB, d8 HD, decent skill points, gestalting means all good saves, favored enemy is nice (Arcanists and Humans/Undead/Constructs might be good in Sharn), and then there's the animal companion. I think the Urban Companion is not only more flavorful for my character, but also less of a headache to keep track of. I'm still seeing if I can apply Improved Familiar to it to make the feature really shine, and if so, how I can boost my effective caster level to determine how good a creature I can get. Depending on how I construct the build, and if Warlock caster level works and can stack with the Ranger, even gestalt-wise, an Imp Urban Companion could do wonders. The other lower level ones aren't too shabby either, and even the benefits of a normal Urban Companion aren't too bad, either (don't have to worry about it dying and losing XP!). Bind Malphas, and have two Raven familiars fly around for me? Fun times.[/spoiler]
I'm also pretty sure I want to go with Whisper Gnome on this one. Definitely works with the stealthy infiltrator idea. Moving away from warforged means no more 'free' armor, but I'm not too worried about that.
Any thoughts on if it's worth making (fixed) Warlock the full-level side or the multiclass side? Are 2d6 and two extra invocations (on a class already getting more than the normal warlock) worth it? Is Imbue Item worth it? It would mean using several of my feats on item creation feats, so I'm thinking no, though maybe in another campaign.