"It's seems your way is to complicated for all of the type of 8051 derivatives." (my emphasis)

By the way, this is not "my way". It is the time-tested means for handling the variable latency issue for all sorts of processors, normally induced by the need to occasionally disable interrupts. The only reason I brought up the whole mess of how interrupt response works, was to point out that variable latency is an issue for the 8051 architecture even if you never disable interrupts.