Shed dormer or not attic conversion

[Reno Che]

I have a 3bd 2 bath cape cod house. The top floor is a 1 bd 1 bath, I was thinking about adding a shed dormer to create more room due to the sloped walls. I didn't know if it would bring a good ROI because eventually I want to rent out the place. I just wanted some thoughts on this renovation. My other thought was taking down the walls and having exposed beams but the beams are sprayed with foam insulation so if anyone has ideas on what to do for that.