I'm thinking the tool might be more useful in the prep phase, before you even reach out to that first investor on your list. The goal wouldn't be to replace your process, but maybe help founders feel more confident before that first real conversation? Especially founders who don't have experienced networks to practice with initially.
Does that positioning make more sense, or do you think even that prep stage isn't worth the effort vs just jumping straight into real conversations?
The issue with using founders/friends is that they're too emotionally invested in you to ask the hard questions in ways the investors will. Founders also think differently than investors. For example, a friend who has built companies before would look at a potential issue and their "operator brain" would automatically come up with ideas on how to address it. As a result, they may downplay the problem. Whereas an investor may laser in on it to test your thinking/confidence.
If you had to practice, making the question submission anonymous (as you can) may help. I know I hate giving harsh feedback to friends directly, even if they ask for it. The sting still lingers around. Not knowing who asked the question could be helpful, but it's possible they would still be able to tell if they know you.
I suggest a simple process, one that I have used in the past:
Ideally by the time you reach your more ideal investors, your pitch deck is much improved and you increase your chances of a favorable outcome. In fact, you could end up with bidding rounds.