I'm thinking of doing exactly this in advance of my next playthrough, which I want to try as an all-evil party. Is there anything built into the game that would prevent this?

My current party is: PC, Imoen, Jaheira, Minsc, Keldorn, Aerie. So I figured when I get to Hell, I can grab Sarevok, export him and boot him, and then he'll be available for the next run as a powerhouse fighter who's available to me the whole game.

Am I missing anything? I assume his dialogue and banter may be limited, but that's no biggie. He has good dual-class potential, what with his killer stats. Plus, he has the "cool" factor. ;-)

You will not be able to export Sarevok: NPCs are not exportable. Their creature files differ, and rely heavily on scripts and events. Besides, Sarevok will have zero dialog and zero voice in BG2 proper. So why not just create a multiplayer game, and create a character with Sarevok's stats and portrait? You can still recruit normal NPCs in multiplayer mode.

The stats can easily be done, but I'm not sure you'd be able to replicate his special abilities.

You mean his ToB Deathbringer attack? In BG2 he would already be overpowered on stats alone, so why would anybody want him to have an attack that deals up to +200 extra damage with a chance to stun the enemy? That's beyond me.

I merely presumed that was desired by OP when they brought up the possibility of importing him.

Now that I think about it, there might also be a problem with trying to replicate Sarevok's ability to one hand a two-handed weapon the way he does in BG1.

Yes, and there is also the issue of Sarevok's Sword of Chaos being gimped, and in the hands of a genie inside Irenicus' dungeon. :/

Oh man, now I have a trippy idea; doing OP's idea and recruiting Sarevok into the party in ToB.

Sarevokception. This needs to happen.

SoA ending spoilers

And near the end of SoA, you could send Sarevok to fight himself one-on-one.

Okay, my mistake...I somehow thought I would be able to use multiplayer mode to pull this trick off. As Hickory said, it's not doable. Or else if it is, I'm not smart enough to figure it out.

Plus, I suppose if he has little or no dialogue, that would reduce the "flavor" of the game quite a bit. The NPC's really come to life in BG2, what with their banter amongst each other and in reaction to certain areas, enemies, etc.

One moment that cracked me up was when the first rehearsal of the play took place in the Bard theater quest. Everyone thought it was horrible, except Minsc. He just couldn't understand why nobody liked it.