Due to the fact that become them home for long term that for the best rather than pay the rent for year and there is a chance to move out for many reasons firstly increase the price of house from the landlord secondly its possible he doesn't want rented it any more , therefore i believe it is a positive situation primarily because you will own this place for good for you and your children in the future and don't buy attention for the rent ,in the opposite of that a negative side it probebly need to loan or gathering money for long time in addition you may want to leave in future that would be huge money loss , in conclusion i suggest if you love the place pay the house ather wise you should rent it for just a brief time