There’s a great chance of her becoming greedy, not because all poor people are greedy.. but because money will be a new experience for her. She will try to use it as much as possible ( an opportunity she didnt have growing up).. and as we all know, we get carried away with money.. since u love simplicity, this situation might not be as simple as u predicted..
compatibility is very important… and it all depends on what kind of a person you are.. will u b able to tolerate her different world.. how easy will it be for u to change her according to the people you meet, your basic standards.. because below peverty line means that shes probably not educated..
its very nice of u to think of the sawab u will get, no doubts mashallah..
but this is a life time commitment, you have to be careful… if sawab is the main reason than there r lots of other ways to do that.. help poor girls get married in pakistan, help poor children, pay for their education etc.
anyhow, good luck. 