Will this memory play affect us NAS users any? I know now that it's recommended that we do not use memory play. So will this change for us?
There are good and bad things that happen when you enable memory playback over a network.
Good: if the track can be fully cached in memory, network traffic is no longer going to affect seeking or potentially interrupt playback.
Unfortunately MC19's memory playback option does not guarantee that the entire track will be cached.
Bad: When you enable memory playback, all the network traffic is at the beginning of the track, so you might then have 3-5 minutes (or longer) without any network traffic.
When it comes to playing the next track, the network might be slow to respond and introduce a delay between tracks, breaking gapless playback. (depends on your network)
With memory playback disabled, it's continually streaming data over the network, so the connection should still be open and gapless playback should be more likely to keep working.
I have to imagine that having memory playback enabled creates a big spike of traffic whereas disabling it means you just have a continuous low-level amount of traffic. This may or may not cause problems for other devices on your network. (probably not though?)
And once again, this would be improved if memory playback was reverted to the MC18 style where it caches the file and not decoded audio, as this guarantees that the entire track is cached in memory 99% of the time. Many times MC19 only caches part of the track that is currently being played.
If you switched to MC18-style caching, while allowing it to use up to 1GB, you could cache the current and next tracks in RAM, eliminating the gapless playback issue because you have the full duration of the current track to get the next track into memory.