Thanks for the idea Kbird1. Actually, I'm only trialling HDA 2016. Its clearly a more sophisticated product than Punch with a lot more control in the users hands, though the toolbars are pretty ugly.
If I was starting again I would buy HDA but I've decided the clincher that would make me pay $200 or $400 to change is that Punch doesn't have custom layers. From what I can see of HDA and what I read in these forums, neither does HDP let alone HDA, and lots of people want it.
For me, I would really like the ability to draw a house as it is, then add a number of changes in layers so I can flick between the before and after view. Yes you can create two plans, but I often do a quick mock up to show the changes, then flesh out the detail to make it realistic. In this scenario, BOTH the before and after plans have to be fleshed out. Ahhh, if only there were custom layers.
So rather than put anyone to any trouble, I'll stick with Punch for the time being.
Thanks for the help.