I don't have a convincing argument for you but just something to mention..
I was told that unless you are pretty hot with *nix the RHCE is a real bitch to pass.. So it was recommended that I look at the LPI and Comptia Linux courses as a foundation before heading to the RHCE..
........I don't buy this one.
I did not take any Unix/Linux course prior to my RH300 course which is and was my only such course ever and I did not take any of the 'lower' ones.
All I had prior to this was about two years of tinkering with Linux on my own and having to learn enough to teach it to complete linux newbies. (More like a sham you'd say)
The RHCE courses are spread out across different levels and topics and so one should be able to digest what was presented before moving on to another one and finally the exam.
A prerequisite of being very familiar with hardware and basic operating system concepts is all that is really necessary.
