I've just been looking at things and the feat progression alone is desirable to a Sorc let alone the metamagic gifts. That's +3 feats a Sorc would otherwise not have. That's a whole heck of alot to spend on Metamagic feats for a sorcerer.
Plus the abjuration is neat, a specialization for a Sorcerer, something normally only available to Wizards, heck an extra spell per day? For every level? Has to be abjuration though...not too bad.
At 10th Level an Empowered Fireball dealing 15d6 as a 5th level spell. Cast that puppy 4 times a day ouch, more to come higher in level as well.
At 12th Level take Chain Feat and begin chaining Hold Person and Haste, fun stuff.
At 14th Level the fun really starts! Improved Metamagic comes into play now all those metammagiced spells are now cast one level lower!
An Empowered Fireball/Lightning Bolt at 15d6 (cast only as a 4th level spell now!). A Chained Haste or Hold Person as 5th level spells (chained haste being more or less identical to the 6th level spell mass haste!). A Chained Polymorph Other as a 6th level spell. Empowered Explosive Cascade for flexible area effect damages, need to fireball into an intense melee? No problem! As a 5th level spell do 15d6 to exactly who you want to, 5ft square/lvl, phew! An Empowered Firebrand as a 6th level spell doing 22.5d6 damage, 5ft rad burst/lvl. for slightly more sparse melee's. An admixed fireball doing an inferior 20d6...
Chained Hold Monster is also an option here as a 7th lvl spell, Empowered Chain Lightning dealing 21d6. If improved metamagic ability stacks with feats used then an Admixed-Empowered fireball would deal 25d6 of damage as a 7th level spell. Mind you, all this is only at 14th level.
Suddenly, at 16th lvl we have an Admixed Firebrand for 30d6 cast as an 8th lvl spell. We also have an Admixed-Empowered Explosive Cascade at 25d6.
At 18th level one could cast a Twined-Empowered Firebrand for 45d6 (albeit 2 saves) as a 9th level spell... At 20th level an Admixed Chain Lightning would do 40d6 (only 20d6 to folks within 30ft though,

) An Empowered Horrid Wilting dealing what? 30d8? Pretty Nasty I'd say, all of this based around evocation and metamagiced Sorcerer style, ack.
I got green in the face just calculating all these out. Combine the extra feats gained from the Incantatrix PrC add in Energy Substitution: Sonic and Admixture: Sonic, or forgo that and just take Dismissal And Banishment and you don't even have to worry about Sonic energy for those darned devils! They are Abjuration spells afterall...
What do the rest of you got? This is what I worked on the other day, any flaws? What else am I missing? I don't think the Improved Metamagic ability should stack, it should be more along the lines of any "meta-magiced" spell is reduced by one level no matter the number of feats used.