GEEB

Thanks for your reply Matt, and indeed your candour regarding where I should invest in the shorter term if I need to have that technical functionality. After I posted I also had the thought of maybe addressing it via a "technical persona" ... now that would be really great! 
Addressing it with a different product would not be a good idea in my humble opinion as you are then competing against "proper" CAD products and the development needed to get it taken seriously would be far greater than just adding limited CAD functionality to Designer - as a persona for example. I personally would not object to purchasing the Technical Persona as a plug-in or add-on as long as the price was right. 
 

Thanks for your reply Matt, and indeed your candour regarding where I should invest in the shorter term if I need to have that technical functionality. After I posted I also had the thought of maybe addressing it via a "technical persona" ... now that would be really great! 
Addressing it with a different product would not be a good idea in my humble opinion as you are then competing against "proper" CAD products and the development needed to get it taken seriously would be far greater than just adding limited CAD functionality to Designer - as a persona for example. I personally would not object to purchasing the Technical Persona as a plug-in or add-on as long as the price was right.