Plan to do this eventually. However, this fundamentally doesn't solve the core problem (for me at least). Versioning nightmares happen when you've got one model that you customized to have three products and your new model has four. To compare to your previous model(s) you've got to keep updating all spreadsheets.

An app like this would hopefully remove some of that rework and eventually allow A/B testing of different fundraising scenarios, or different revenue models with similar fundraising, etc.