I first learned AutoCAD back at version 12. We were fed up at the cost of AutoCAD, no shock, and so tried ProgeCAD. Seamless change over. A big plus was having the two copies. (only one to be used at a time, fair enough) So one on an office computer and one on a tablet I can take to site with me. At Redhouse Forge we design and make feature metalwork. So might be 3m tall stainless gates, or a vanity unit set in the wall or traditional wrought iron, but having the drawing there on site so I can point "this bit!" or make alterations while there can be very useful. We bought a second copy. Our neighbour, furniture designer, bought a copy. Our structural engineer bought a copy. I should be on commission :-) I was talking with an architect in the Library at Willesden Green, London who won't be buying a copy, as he has been using it for years and used it to design the library we were in :-)