After thinking this over during the holiday weekend here in the US, I have one major criticism - the damage system is too "flat" across multiple platforms.
While size is based on the EA DC, the actual damage that a titan can take is based on the "damage status" chart.  Basically, aside from the number of weapons that might spread damage out a bit, every titan has the exact same effective damage capacity.  The only difference in durability between a Warhound and a Warlord are the armor values.
Obviously, a lot can be done with armor values alone, but I would recommend adjusting the damage charts as well.  It's pretty wide practice in wargames to have damage charts with blocks missing (pre-filled/pre-marked/whatever) for smaller units.  So, instead of Warhound titans having minor/major/disabled, they could have minor/disabled (with the "major" damage" removed).  That could lead to a 2-hit kill with bad die rolls, but it would still allow the possibility for taking 4 hits and still having an opportunity to repair.  In addition, having an option to block only some of the squares will be a good way to customize other mid-range war engines as a bit tougher or weaker.
Also in the relative damage vein, the difference in the 3+ reinforced and 4+ reinforced from the Warlord to the Reaver is pretty darn big.  I realize the reactor and shield generator saves remain the same which mitigates it somewhat, but it's still close to 2x the durability against AT and assault hits (I'm assuming the translation to EA already) and 1.5x as good against MW hits (3 hits for one damage instead of 2 hits on average).  Even with equal weakness against TK, that seems quite a bit tougher than a DC6 v DC8 (or even 6 v 9 from 40K).
For the Warlord, I suggest leaving the legs at 3+RA but leave the other saves as the Reaver.  Since there is a pretty good chance of hitting the legs from any angle, that will give it more durability against a fairly common hit, but not make it as impervious across the board.
Of course, that suggestion is sans playtest, so maybe I'm wrong about the relative toughness of the battle titans.  It just seems like a big jump on paper.
As another way to adjust relative toughness, you might figure a way to have the size factor into repair rolls.  I'm not quite sure how to work this (maybe something like the maximum number of repairs in a single turn would be 1/2 the size?), but a system based on size would have a nice advantage of helping out larger things like the Ork Gargants automatically so you could keep the relative effects of damage charts similar in scope.
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Ork Gargant ideas:
Hit locations
Front 1- feet 2-3 body 4-5 weapons 6 head
Side/rear 1- feet 2-3 body 4 weapons 5 boiler 6 head
Damage
Feet - as Imperial Legs (though possibly with just an "immobilized" effect rather than critical damage).
Body Minor - "Auxiliary" weapons (if present) cannot fire. (Great Gargant Big Gunz, Krawla skorcha turrets, Kustom Gargant AA guns, etc.) Major - Belly gun (if present) cannot fire.  Starts 1 additional fire. Disabled - Critical damage.
Weapons - as Imperial
Boiler Minor - Starts d3 additional fires. Major - Lose 5cm move.  Starts d3 additional fires. Critical - Critical, modifier to damage roll.
Head Minor - Gaze of Mork cannot be used. Major - Gaze of Mork cannot be used. Disabled - Head blown off. All further weapons fire is -1 to hit. Roll an additional point of damage. Any further head damage is rerolled.
Fires - Fires could work as "negative repair rolls" (i.e. 4+ on a fire roll in the end phase causes damage) spawning random damage on the side/rear chart.  Fires can be put out as a repair roll.  Roll for potential fire damage before repairs in the end phase.
I think with the relatively high probability of hitting the body and the fact that many Gargants won't be disabled by minor body damage that it builds in extra durability when compared to the Imperials.  Also, the non-kill head critical slows it down. If you add in feet as a "disabled" instead of critical damage that would boost it even more.  Something that would be strongly affected by body damage, like a Great Gargant potentially losing both auxiliary weapons and the belly gun, could be adjusted with armor saves, e.g. 3+RA for a Great Gargant body.  Supastompas can have 2-step, minor/disabled charts but you could potentially leave minor/major/disabled on the body damage.
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I'll get back with the upgrade ideas once I get more caught up at work.
_________________ Neal
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