There's not that much real-world activity yet with that firearm. It's new enough that operators using it are not under much public scrutiny. Supposedly it's in use by at least 15 countries now so it should be a matter of time before reports come in.
Not really an answer to your question but you might try using the search feature at the top right of the page as this round has been discussed in depth (in pistol forum, I believe)
Small Arms Review did an article and review on the P90 in the August 1998 issue, Vol 1 No. 11 that may be of some interest to you.