I am sure the OS plugs work great for many people as it's an ultra hot plug that will essentially force the engine to stay runing even when your tuned on the rich side. All I am saying is I run at a MUCH higher altitude than most and if you know how this effects an engine you know that I have to run very hot plugs and/or pull out headshims. If I can get the engines running on HOT nova and RB plugs there should be no problem with making it run great at sea level with a hot plug and stock shimming. Adding a shim is much like running a colder plug. So going up a headshim and hotter in plug is basically countering or compensating for the other change. If your engine is over shimmed you have to run a hotter plug to keep it running. If your shimmed low for max power you will need to run a colder plug to avoid detonation.

Below is an RB plug on the left and an OS on the right. I know personally I will run what is made for the engine. I have never tried an OS plug myself and after seeing them side by side I myself never will try an OS plug. Again I am sure the guys you talk to know what they are doing and if they are the ones that are going to help you if and when you have issues you may want to do what they say. All I am saying is give a hotter RB or Nova plug a try before you start adding shims and using OS plugs.