This paper introduces an end-to-end framework for efficient computing and merging of Monte Carlo simulations on heterogeneous distributedsystems. Simulations are parallelized using a dynamicload- balancing approach and multiple parallel mergers. Checkpointing is used to improve reliability and to enable incremental results merging from partial results. A model is proposed to analyze the behavior of the proposed framework and help tune its parameters. Experimental results obtained on a production grid infrastructure show that the model fits the realmakes pan with a relative error of maximum 10%, that using multiple parallel mergers reduces the makes pan by 40% on average, that checkpointing enables the completion of very long simulations and that it can be used without penalizing the makespan.