Matt,
As previously stated, I was provided the specs for the F4 cam from Cindy or James @ FWDP. I never have had the opportunity to degree a F4 camshaft in. At the time they were given to me, I assumed the specs given were at the valve, as it wasn't specified. Without given that info, and looking at it on paper only, I elected not to purchase one because at the time it seemed to be WAY smaller than what I was looking for. Warren was provided the same specs as I posted. Warren, having ran a F4, reasoned that the specs posted must have been at the lobe, because he knew it had more duration at .050 than what was posted. So it is assumed at this point until we can get a F4 cam degreed at the valve, that the specs posted for the F4 @ .050, in reality would be @ .087 at the valve. We are waiting for F4 specs at the valve to be posted so we can have an apples to apples comparison.
What we appear to know for sure is the R5 has +.020 lift on intake, and +.034 lift on exhaust over the F4's posted specs. and that it has a smaller LSA than the F4. It does appear that the R5 could have a bit less duration as you stated, but I would like to see those specs at the valve before declaring that as fact.
Todd