@sjpknight - Yeah our roles do sound similar and I find the scope of my role growing constantly. In any direction that is useful to the team. I agree fully with your comments.
Bill commented on twitter "To me 'Technical Testing' is not about having technical skills, it's about a focus on testing against technical risks with a product. Technical Risks related to the technology stack for instance. This may mean you require so.e technical skills to achieve this" .
I've been exploring the areas detailed by yourself, Danny and Lim but haven't looked at formally assessing the product in the way Bill mentions. It resonates though. I have advised based on previous experience but I'd like to know how it is done formally. Is it a case of learning the applicable stack and understanding the risks? Is it feasible if you aren't an Architect and if there are any resources that are helpful?