What are your preferences with forms?

[eluser]simshaun[/eluser]
In the past, I always had separate forms for Adding and Editing something. In many instances, I have additional or different fields on the Edit form.

Now I've got a third form to throw into the loop. Its becoming a pain in the butt to simply add an additional field, having to modify all 3 forms in up to 3 spots per form.

Do you prefer having a single form with conditions for "Edit" specific fields, or do you prefer having separate forms for each action? I can see advantages and disadvantages to both methods, so what are your opinions?