Yeah, it is flexible, but that's not necessarily a good thing. At least not for the storyline. Sure there are other PCs that you could pick up, but that doesn't necessarily fit into the plot. Other than Imoen, Khalid, and Jahiera, all the other NPCs had no plot significance in BG1. In BG2, the same goes for most of the NPCs. In fact, Keldorn and Anomen don't really have any plot significance. Considering what I heard of things to come, the party with the most significance to the story would be Jah, Minsc, Imoen/Yoshimo and Vic (for Underdark later though she can't cast some of the really good healing spells and I wouldn't send her into battle for spells like Harm). From a storyline perspective, until you get Imoen back, you don't have a decent mage, and when you do get her back you're kind of screwed because she'll be at such a low level. This is why I think that the PC is geared towards being a mage in BG2. Furthermore, especially compared to BG1, the mage has (IMO) been more worked with than any of the other class. There are a -lot- more new spells for the mage, and a lot of nice equipment. And they also improved the cleric class quite significantly (which I'll mention later). As for BG1, you had a poor selection of clerics. You had the evil Vic, the Neutral Branwen (and Quayle later with his 13 Wisdom) and the Good Yeslick, none of which were plot essential. Being that the game was designed for a good party (it seems like everything you did raised your rep, I had a rep of 20 by the end of the mines), and the only good cleric didn't come along until over halfway through the game, coupled with the fact that out of all the Tomes and Manuals, there were 2 (well 3, but one is needed for a quest) Tomes of Wisdom, along with a really nice hammer early in the game (the one from Basillus). It would seem that a cleric is better choice for BG1.
In short, that is why I think (according to keeping a fluid storyline) the PC is geared towards being a cleric in BG1, and with the improvements done to the cleric class, as well as the improvements to the mage class, it's why the PC is geared towards dualing to a mage in BG2. Originally I thought it would be a dual thief/mage because imoen is a bit lacking in the thief skills, but really, I only need her to disarm traps. I can cast find traps/invisible (as a cleric mage) to scope out a level and then she can turn invisible and follow me to disarm them.
Maybe I'm reading too much into this, but considering that I just moved here, have no cable yet, and am still waiting for the rest of my stuff to arrive so I can have the box with BG2, along with all my other good stuff, I think this is a good use of my time.
