I agree it is definitely the easier option however some of my fellow colleagues are not very excel savvy and I can see confusion developing with multiple sheets to reflect multiple scenarios. If you don't mind building the macro i would prefer to use that.
I was faced with a similar problem when building an Interest/Capital/Time model.
I ended up using extra cell for the calcs. Look at the attached file the light blue cells are input, you can input any 3 of the variables and always get the full set of results. The solution is not very elegant, but it works, you can place the calcs on another sheet or hide them. I hope this helps. You can of course achieve this with VBA as well.
