In the formation of sulfur hexaflouride, does the reaction at constant pressure or volume proceed more spontaneously?

I've done the calcs to show that at constant volume, it is slightly more spontaneous, but I can't seem to find a good reason why... it might have somehting to do with Le Chateliers Principle but Im not sure... can you make any suggestions?

If the reaction is spontaneous, it is spontaneous. What does "more" spontaneous mean?

Do you mean which has the greater free energy? If you mean that, then why is one calc greater than the other? The answer is in the numbers, it seems to me.