I have been using the open source version of SoapUI for a while now to test .net web services. What I have noticed is that SoapUI uses milliseconds in its WS-Security timestamps. The security of the web services I am testing (and doubtless other .net users) is such that milliseconds in timestamps causes all requests to fail. .Net timestamps by default don't include milliseconds. I have downloaded and modified the SoapUI source in order to remove the millisecond component. However it would be great if this could be included in a future release as a user conifgurable preference somewhere. This would open up SoapUI to a larger number of (.net) users.
I will pull together and document my code and submit it to you in a couple of days.