There is a sort of ambiguity when people discuss QM as being subjective. It is not "subjective" in the same way that word is used in general language. There is nothing subjective about the fact that the two slit experiment results in interference. It has nothing to do with who is watching it. It has to do with what happens when a particle interacts with another particle. That creates interference.
The word "subjective" is already ambiguous. A "subject" in Kant is the observer. A "subject" in England is a subject of the king--as in the "king's subjects."
So what is meant by subjective when people use the term in QM? It means probability. You have a state of a system and then you have something that acts on it. Then you get a new state. The probability of the new state occurring is what people mean by the word "subjective."
It is better not to read what philosophers write about Quantum Mechanics. Kelley Ross is right that Kant provided essential insights, but since then there have been very few people that work in philosophy that understand Physics well enough to say anything intelligent about it. And that means that few philosophers are competent to comment about reality. They might be able to give a course in philosophy, but to say anything intelligent about the nature of reality they are far away from.
[I should mention that Quantum Mechanics (Heisenberg) deals nicely with interference and you don't need the Schrodinger picture for that. See this post by Lubos that does the actual calculation To derive interference from the Heisenberg Picture
Here is an important quote from Lubos: http://motls.blogspot.com/2012/11/why-subjective-quantum-mechanics-allows.html?m=1
Here is an important quote from Lubos: http://motls.blogspot.com/2012/11/why-subjective-quantum-mechanics-allows.html?m=1
