On your second point the computer, wires, etc. for Roon could cause effects not present in your Sooloos core/store.
Even Meridian themselves have said on multiple occasions that Audio Quality is determined ONLY by the Endpoint itself... and not by the "Core"... as Stream transmission by Ethernet obfuscates any effect that Processing within the Core might have
And in monetary terms, they said that using the £6,000 MC600 would NOT result in better or different audio quality than using the £1,500 MC200
However, using the 818 as an Endpoint would result in better audio quality than using an MS200 as an Endpoint
And Roon, being ex-Meridian, have followed that logic in using Ethernet to isolate the Endpoint [808.6 in the case above] from any impact that Processing in Core might have on the Endpoint