Hi frog,
I have looked into the use of STP Cat 7 cable instead of Masterlink and I have not been very impressed with the performance. In particular, the smaller conductor sizes in Cat 7 cable seem to cause the +15v and -15v voltages on the blue and pink supply voltage wires to reduce over fairly short distances, meaning that the link room products display errors or lose communication. Hence, I would always recommend the use of Masterlink cables for ML products, as these will give you the best performance and reliability. Masterlink cables and connectors will continue to be available for many years to come (even if B&O stop supporting them!), you can see these here:-