I just upload on my home page a paper named "Single Tone Measurements of Nonlinear Distortions in Wideband RF Amplifiers". It might be helpfull to you as another look at IP measurements of wideband devices.I also use my Perseus as a measurement unit - as a calibratred spectrum analyzer with exceptional dynamic range which makes these measurements much easier.
The link is www.lz1aq.signacor.com . I am not giving the exact link since I soon will reorganize my page and the links to specific papers might not be the same.
73 Chavdar LZ1AQ lz1aq@... www.lz1aq.signacor.com