You might try using the forum's search features since those flours have been discussed before. However, I think your best bet is to get in touch with the suppliers of the flours you mentioned and ask them for spec sheets. As an example, if you go to the Pillsbury webpage at http://www.PillsburyBakery.com/GeneralMills/SalesForce.aspx
and look for the sales rep in your area and send that person an email asking for the spec sheet for their 4X flour, you should get the information you are looking for. That should give you the protein percent and other data on the Pillsbury 4X flour. You can also call the sales rep and if that person is unavailable, leave a voicemail asking for the spec sheet to be sent to you (of course, you will have to leave your email address). One metric that you may have a hard time getting is the rated absorption values for the flours that you are looking into. Most millers do not put that information in their spec sheets (Pendleton Flour Mills and King Arthur are exceptions). However, if you are able to get the protein content, moisture content and the dietary fiber, you might try using the Hydration Calculator in the pull-down menu at http://tools.foodsim.com/
to come up with the absorption values.