Another s/pdif digital cable thread

When I set up my system and cabling some years back I was blissfully unaware of difference between 75 ohm and 50 ohm BNC connectors.  I just thought BNC was BNC.  Most of my digital gear already has 75 ohm BNC female connectors for s/pdif inputs & outputs.  Some, however, has RCA sockets.  On close inspection I recently discovered that the cables all have 50 ohm RF connectors.  And a couple are 50 ohm BNC at one end and RCA at the other. 

IOW, it's a connector and impedance mashup salad and I want to sort it out right.  First, the 50 ohm connectors will get scrapped and replaced by proper 75 ohm connectors.  Then I'll use 75 ohm BNC => RCS adapters instead of the BNC/RCA frankencables.
So here's the question:  how much degradation do all these mismatches create?  Seems like there should be a ranking of these scenarios.1. Proper 75 ohm BNC + 75 ohm coax everywhere.  The right way, next step.
2. [50 ohm BNC connectors + 75 ohm cable] to [75 ohm equipment connectors].  What I got now.
3. [75 ohm BNC + 75 ohm cable + RCA] to connect "mixed" equipmen.  Also what I got now.
4. [75 ohm BNC connectors + 75 ohm cable] + BNC/RCA adapter to [mixed equipment connectors] .  Next step.

Any comments or suggestions would be great.  I'm hoping for a big improvement - but time will tell.  Thanks,