Quote from Barth Vader:
Sorry for the delay......Every Saturday we go to the grocery market. I have come to understand that if I do not provide energy [food] for a biological system [me] it will reach a state of equilibrium or maximum entropy [death]
So where were we.......oh yes, open systems.
The second law of thermodynamics is an empirical law, directly observable in nature and in experimentation. To my knowledge [ I will admit that I am more familiar with the philosophical perspectives of science than the actual mechanics], the vast majority of scientific experimentation is conducted upon "isolated or closed" systems. To argue for macro-evolution based upon the results of observation on isolated systems would be a severe handicap to the macro thesis, especially when entropy is the object of the experimentation.
Biological systems are open systems, as you have intimated, as their boundarys' are crossed by matter, such as my food intake example [ I spared the board any example of waste output !]
To argue that it is possible for macro-evolution to occur in open systems, would require that these systems show immunity to the first and second laws of thermodynamics, and furthermore, we should be able to observe the negative entropy causation in operational effect as we speak. I am not familiar that this has been observed.
To follow your argument of open systems receiving a get out of jail free card from the empirical demands of the second law, which would require these systems to be systems of negative entropy change [ not just conservation], which obviously requires the energy source to be of such magnitude and quality to produce a positive entropy change in the surroundings of the biological system.
In other words, the energy source for the open system must have "ordering" production capabilities. Simple energy from the sun, for example, is not sufficient to explain the "order enhancement" required for the macro-evoluntionary thesis to
produce a surrounding that enables order from dis-order [especially as it relates to the first law], especially when we consider the primordal starting ground that these super microbes began their ascent.
It would appear, that at the end of the day, creation advocates and macro advocates must walk upon the field of speculation and faith. For me, the Creator has provided the order for our existence, and the laws which science observes. Science has yet to observe macro-evolution or its uncanny presumed ability to escape the "order" and "laws" contained in the creation itself.
Any reasonable physicist will tell you that current laws of physics may not apply to period of creation of the universe.