The nitrous will drop the temperature of the air charge similar to that of water/methanol. Horsepower attributes will be the similar as well. The cooler charge, combined with the introduction of oxygen into the air stream will safely allow increased power levels (when the appropriate amount of fuel is added).
...but, the only drawback with nitrous in compared to methanol is that you don't get the added benefit of increased octane . Adding methanol injection to 91-Octane pump gas can boost octane levels into the 116 range, allowing you the benefit of added timing along with the cooler charge.
They both have their positive and negative points. You don't have to worry about fuel puddling, or damaging backfires with methanol (which to be honest probably wouldn't be an issue with a 50-shot anyway) like you do with nitrous. But then again you don't have to worry about corrosive effects with nitrous like you do methanol.
Pick your poison.