Many people think CHI did that to confound the copiers. Sort of amusing when you consider they're copying a Ford 335 series platform themselves. Doesn't make sense to me cuz it's just as easy to copy that too. It seems more likely to me they did it to enable/gain another .25-.30" port roof height.
Despite my experience I think they make a good product and save a few quality problems which all manufacturers suffer from time to time, in my view the only advantage if any they offer over my 30+ year old high port Ford heads is combustion chamber design but I still say the rest is more about who is working the parts than the parts themselves.