I agree with everyone on this thread about body off restorations. I think it depends on our motivation, your mechanical aptitude, and the condition of your frame.
If your frame shows serious rust, then obviously, it must be addressed. If you are a restorer like Certified and/or you are driven to know all the ins and outs about your car - and as JB says, you are committed to finishing it - then a body off is a possibility even if the frame seems in good shape.
If you aren't sure of your commitment and the frame and there is no serious rust, I think that embarking on a body off is a mistake for the reason JB stated. You will miss out on a lot of driving enjoyment and regardless the condition of your frame, motivation, etc., the loss of that driving enjoyment should be factored into your decision.