Hi Dick,
In my experience, lowering the base of class 'E' 4000ft will provide zero benefit to IFR aircraft, it will in fact restrict the options available to you...if you are IFR in IMC, you will get no extra benefit if class E is below the grid LSALT. sure you will be in 'controlled' airspace lower, and separated from other IFR 4000ft sooner, but If you are not visual I will not (prohibited in Mats) clear you off a published ATS route. That means no deviations off the published route until OCTA or above the LSALT. Think about the potential complications involved with that. Expecting Amended route clearances prior to departure, a useless MSA, and no movement to position until below A045.
For multiple IFR arrivals, 4000ft will not increase your safety, it will unnecessarily complicate it.