The Revised Specialist

Specialist wizards in 2e are derided as being kind of bland; their spell list is essentially a mage's spell list, but with less variety, and a bonus spell slot. While they're markedly better at their specialty than others, and choosing the right specialty can result in a more potent wizard (the bonus spell really helps), they're, overall, kind of uninspired, and, aside from the bonus spell, not terribly different from playing a straight mage who just so happens to never get spells from certain schools.

So, I have a proposal to change them. I've mentioned it several times as an option, but wanted to solidify the ideas, and solicit feedback on how to tweak it to a good point.

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Specialist wizards are those wizards who have chosen to concentrate on a single school of magic, to the detriment of one or more other schools. While not completely incompetent at those other schools, they are markedly less able than a generalist might be. When considered from standard mages, Specialists have several changes.

Benefits
1) All spells of their chosen school are counted as one level lower, thus easier to learn and cast. For example, a conjurer may choose to learn Melf's Acid Arrow as a 1st level spell. If the game has the equivalent of "10th level spells", then specialists may learn and cast those spells when they receive 9th level spell slots, provided they meet the other requirements of those spells in that setting.
2) They have a bonus spell slot to be filled with a single spell of their specialty from what is now "0th level". That same Conjurer may choose to memorize Armor in their 0th level slot. If they devote a 1st level slot to 0th level spells, they may memorize two spells in that single slot.
3) For purposes of their specialty school, their intelligence is counted as two points higher. This affects chance to learn spells, maximum number of spells known, and maximum spell level. If using a system which grants additional spells or spell points based upon Intelligence, this benefit likewise applies only to spells of their school.
4) Whenever a new spell level is achieved, may choose 1 common spell of their specialty. If the game allows a free spell to be learned at every level, this is an additional spell, acquired only at a new spell level.

Hindrances
1) As outlined in the Player's Handbook, being a specialist has higher attribute requirements.
2)All spells of their opposition schools are counted as two levels higher. Thus, the aforementioned Conjurer might learn Melf's Acid Arrow as a 1st level spell, but would be unable to learn Magic Missile, an Evocation spell, until 5th level, as it would be considered a 3rd level spell for a conjurer. Spells that are partially opposition spells are counted as being of the opposition school, unless they are also part of the specialty school, in which case the specialty school trumps the opposition school.
3) For the purposes of opposition schools, their intelligence is considered two points lower. This affects their ability to learn spells, the maximum number of spells known, and the maximum spell level. If the specialist has an intelligence of 9 or 10, this will prohibit learning spells of their opposition schools.
4) If the game allows a free spell to be learned at every level, it cannot be of one of the opposition schools; they may still learn them (with their lower effective intelligence).

By way of example, consider Marco, a 5th level human Conjurer. He has a 15 Constitution (required of a conjurer) and a 15 Intelligence. For Conjuration spells, his effective intelligence is 17, so his maximum spell level is 8th, with a 75% chance to learn spells, and capable of learning up to 14 spells per spell level. Since he can learn 8th level spells, and being a Conjurer drops the effective level of Conjuration spells by 1, he will be able to learn any Conjuration/Summoning spell in the Player's Handbook. For Invocation/Evocation and Greater Divination, his effective intelligence is only 13; no more than 6th level spells (which would be 4th level spells to a generalist), 55% chance to learn spells, and no more than 9 spells. For all other magics, he has a 15 intelligence... 7th level spells, 65% chance to learn, and 11 spells per level, maximum. This means that no more than 9 spells from each level can be greater divination and invocation/evocation, and 11 spells, total, that are not Conjuration/Summoning. Above his 11 spells of other schools, he can have 3 spells of Conjuration/Summoning... he may choose to have 14 Conjuration/Summoning spells, or up to 11 of other schools, and 3 Conjuration/Summoning.

As a 5th level wizard, he has 3 1st level spells, 2 2nd level spells, and 1 3rd level spell memorized, plus a bonus "0th level" Conjuration spell. His spellbook may look like this.

0th level: Armor, Find Familiar, Grease, Mount
1st Level: Glitterdust, Melf's Acid Arrow, Summon Swarm, Protection from Evil, Color Spray, Comprehend Languages, Friends, Charm Person, Change Self, Detect Magic, Read Magic, Chill Touch, Spook, Sleep (14 spells total, but 3 are Conjuration/Summoning, so are within the 14 spells per level maximum of his effective 17 intelligence; no spells are Invocation/Evocations, as they are counted as 2nd level spells)
2nd Level: Monster Summoning I, Flame Arrow, Continual Light, Deeppockets, Levitate, Ray of Enfeeblement, Mirror Image, Blur, Spectral Hand
3rd Level: Evard's Black Tentacles, Dispel Magic, Protection from Evil 10' Radius, Fly, Stinking Cloud, Hold Undead, Magic Missile, Shield (Magic Missile and Shield remain worthwhile learns, even at 2nd level)

He might memorize something like:

0th - Grease
1st - Armor, Mount, Melf's Acid Arrow, Detect Magic (he can memorize two 0th level Conjurations in a single 1st level slot, in addition to his bonus 0th level spell)
2nd - Monster Summoning 1, Mirror Image
3rd - Evard's Black Tentacles