That is time and slides wasted. More time efficient and effective ways to tackle this:
- A couple of really professional and serious looking slides with the highlights, plus an invitation to visit your web page for all the details
- Discussing the weakness of your competitors verbally and informally: it is hard to put this on paper. Suggest your client some tough questions to ask when they meet the competition. Note that this is actually a presentation design challenge, without creating the actual slides. You need to have this story prepared, maybe even with the help of a “spontaneous” flip chart sketch
Now spend the time you gained on the issues that really matter: are you expensive, is it hard to switch supplier, etc.? Preaching to the converted is never a good use of time.