Bloody hell. You cant swing the word 'Reincarnation' around in here without knocking into a big tin of Karma.
Karma, as most people understand it, is an imaginary scorekeeping device. Karma is calculated through an external value system which controls through the application of guilt and promise of reward. Heaven and Hell do a similar job in the christian world.
I believe karma, as a concept, is a valuable one: that which you sow, you reap. The bit I take offence to is the imposition of the external value system- since everyone's experience of reality is their own, it makes more sense to develop one's own value system.
If the ultimate aim of reincarnation is to fully experience your own divinity, surely taking someone's (or some organisation's) values wholesale and making them your own is about as sensible as thinking you can learn to cook by microwaving a TV dinner.
Developing your own value system is hard work. It takes constant vigilance, compassion, and respect for your own divinity and then, when you lapse, humility and forgiveness. Like moving house or servicing your car, for most people it's just more convenient to have professionals do it for you.
An easier way to your own values is to start with some pre-existing ones, and then look at them critically, one by one. If you want to service your own car, you start with the easy jobs, but of you keep challenging yourself and trying just one more, slightly more difficult task, eventually you'll have a thorough understanding of how the car works. Its the same with values. Just keep questioning one or two things you 'believe' until you're confident you believe them. Or throw them out if they're not sensible.
Anyway, I just happen to believe that figuring all this out for yourself, learning to experience your own divinity, takes a long time. Definitely more than one lifetime. And that's where we start swinging that R-word around.
