Personally I don't think Vin would turn TLR 2.0, but whether or not her actions would be seen as "good" or not is what she actually did with her power. If she took the same route Rashek did, and made herself immortal, and then did her best to squash anyone from figuring out how to end her, then she would definitely not go down history as a good guy.
Whether she would actually make anything better is a point of debate, because if we remember Rashek didn't really know what he was doing when he "defeated" the deepness, and ended up wrecking the planet. I assume that she would learn from his mistakes, and attempt to rectify them, but whether she would succeed is a bit unknown.
The trickiest bit wouldn't really be what she did to the planet (assuming she doesn't accidentally wipe out all life on Scadrial), but her long-term effect on society. If she let herself die a mortal death, then there's a strong possibility that some yahoo would let Ruin go come next millennium. And we all know what happens when you try to keep yourself alive and on top of the world for 1000 years, people get mad.
In the end I don't think it really could have gone any differently than it did, and if it did go any differently, we'd probably see either see a repeat of The Final Empire, starring Vin as TLR, or a repeat of The Hero of Ages, except without a team of heroes to stop the apocalypse at the last second.