The engine has weak bottom end torque to start with and it is even worse when you change the cams. The OHC design of the 4.6 has limited rpm range which should be a benefit of OHC but Ford did not design the head correctly to allow some high rpm range. Spending $1k+ for cam and labor if you don't do it yourself to gain 6-10hp is just crazy since you will need a Tuning device and other parts to allow the cams to give you that 6-10hp. I just don't see the cam change as a real benefit and even on a built 4.6 I have never seen any real HP improvements. I am sure I have read magazines that have done the cam swap they got 14hp@6200. Even if you get that 14hp how can you support the cost per HP. I have done the install with the correct tools and it is a lot of work for such little power improvement.
Most NA cars are picking up 20-25rwhp with cams and a tune. Cost effective? Well, thats a choice each person has to make. mod motor parts arent cheap. I picked up 15rwhp/15rwtq with a set of cams, and the curve was great. Oh yeah, this was untuned. I proboly would have had another 10hp with a tune. As far as an ohc motor limiting the rpm range, thats simply not true. Many of the top NA guys on my ET List ( http://forums.stangnet.com/showthread.php?t=727174&highlight=stangnet's ) shift there cars at 64-6600rpm with the stock bottom end. Bill Putnam(Mustang92) and the fastest bolt on 2v car to date, picked up .3 tenths with vt stage 1 cams. It might shift the powerband slightly higher, but thats where getting a low gear in the car helps.
As far as reading magazines, dont bother, they are a waste of time and very biased due to the parts and companies that advertise there.