Thanx for all the input! I will provide some more info:
My character is now a 3.0 Mnk1/Pal1/Sor7. We are a few weeks away from returning to our Return to the Temple of Elemental Evil campaign, only now using 3.5 rules. Obviously, a straight conversion will cause the character to lose his Divine Grace, Evasion, Lay on Hands and Divine Health.
I created this character because I when 3.0 came out I wanted to try the Sorcerer class. I wasn't too charmed by the concept: minimal spell selection and slower spell progression, but I liked that they finally made a class that relied on Charisma.
Because I considered Charisma a suboptimal ability (you gain nothing extra from it) and Charisma related skills are unreliable (even 6 Cha Half-Orcs can Intimidate or Gather Information). I looked for some synergy and found it in Divine Grace. I then thought about a character that would (initially) think of himself as a (holy) warrior but would slowly learn to appreciate his arcane powers and turn into a full-fledged sorcerer. He would also focus on Diplomacy.
I came up with this background: His Father disappeared during the war with Iuz, his mother brought him to a monastery because she could not afford to raise him. When he came of age he left the monastery, desiring to join the crusade. He signed up for a military order of Heironeous, but was expelled when his sorcerous powers manifested. He then took up adventuring. He sees his Sorcerous powers as god-given by Heironeous. He would certainly not be a religious fanatic, but a natural leader who feels insecure and unworthy of a position of leadership, even though he naturally gravitates towards it.
I want him to continue primarily as a spellcaster. He has been fighting less and less the last few levels, and I was (in 3.0) satisfied with the contribution he made to our party's efforts, even if he was a substandard caster. The fact that he had tremendous saves (and evasion) helped him survive several encounters that would have been lethal to a single-classed Sorcerer in our (somewhat self-centered) party.
I did consider the Eldritch Knight PRC, but I didn't think it fit him. It is central to his character that he has turned away from the melee path. I am currently considering making him a Pal2/Sor7 or a Clr3/Sor4/Mystic Theurge 2. The last combination sadly loses him yet another spellcaster level, but keeps in his 'Holy Warrior through spellcasting' philosophy.
I do think raising the Paladin's Divine Grace and Monk's Evasion ability to 2nd level in 3.5 where good ideas. I just had hoped that the Book of Exalted Deeds would have contained a +1 caster level PR that fit a Paladin/Sorcerer combination that already had given up 2 lvls of Sorcerer to a Paladin class.
