Gary,
1. Marker lights? I think is one.
That's not been a problem in any of my 8 lashups, several of which areP S3 only, under DCS 5.0 or later. DCS 5.0 allowed customization and saving of lashup member settings via the FSV soft key.
2. Unable to to lock sound volume to match each other.
Again, not a problem in any of my 8 lashups using DCS 5.0 out later.
3. Occasionally one engine in a lashup will lockup and not run in either direction, if you don't shut it down in time, the PS3 board will burn up and the burning electronics smoke/smell will be seen.
I'v never had this happen in DCS 5.0 or later.