What is the best way to accurately assess the knowledge level of a group of about 50 people?

You forgot the first step: What’s the required level of knowledge? Get that specified, then assess where your team is at compared to that and you’ll have your gap to address.

Send out a zoomerang survey. They have free accounts. Or if your team uses SharePoint, there’s survey capabilities on that as well.

If you can, the most fun is to get them all to stand in a room, start asking them questions about which product they would recommend for different things and ask them to divide themselves into groups to visually see the collective wisdom. What product(s) would you say is best for someone with this specific need? Get some answers and have the answer A people stand here, B stand there and No Opinion stand over there and maybe Other stand over there. Then ask more questions about other products and features and see how they regroup. It’s fun and can be very illuminating. You’ll see what the conventional wisdom is and who has no clue quickly. Using language carefully is important so people don’t feel judged. No Opinion is easier for people to act on than I Don’t Know, for example. Best for conferences or large gatherings.

Here’s a good resource for more info on TNA’s

Perhaps a complete product retrain is in order, with an overview of competitor’s products so they can learn about product differentiation.