Tweeter Capacitor Upgrade (Coincident PREs)

I wonder how the PRE would sound with some paper in oil caps? It only uses two so it wouldn’t be that hard of a mod?

Do not willy nilly change coils!

You have to match the DCR or you can make fundamental changes to the tone, and not in a good way.

For the woofer coil DCR sets the bass level, as well as helps with baffle step. Meaning, you must measure the DCR and only replace with equivalents (within reasonable tolerances).

In parallel to the driver, changing DCR without adding R can really muck with the impedance curve and have unintended consequences.

Good article on capacitor comparison and listening tests. http://www.humblehomemadehifi.com/Cap.html
My speaker manufacture uses extremely tight tolerances so as Erik mentioned above just the differences in tolerances can shift the cutoff frequency substantially. One of the reasons I chose the capacitor I did was tight 1% tolerance along with excellent sound for expense ratio. I am a Mundorf Supreme Silver Oil guy myself for preamps and Supreme in speakers.  Paper in oil capacitors typically have 10 to 20% tolerances. So do pay attention to attempting to get a reasonably tight tolerance match of the capacitor you are replacing.  I have had good experience with Sonic Craft as a seller, large inventory, good prices, fast shipping and they do capacitor matching for a minimal fee.    

Warning: Do not measure capacitance value when tweeter is still in circuit. To duplicate its value precisely, I measured the capacitance value before I ordered replacement. Since the capacitance meter puts a signal out to measure capacitance value it can fry you tweeters! Don’t be a dummy like me, remove the capacitor from the circuit. My mistake cost me a few hundred bucks; however, I was able to replace the ribbons later and now have a spare set of tweeters. I am good with my mistake now, but when I looked at my tweeters and saw those shredded tweeters I was kicking myself.

I agree with Erik you only change inductors if you have the correct 
inductance reading or label on the inductor. The Jantzen Copper foil waxed paper inductors are a great buy and close to the best out there .wiring cap, for sure better Gold over Copper Connectors 
vs the stock Gold over Brass ,4x the conductivity ,
And  rewire it with a Quality Wire ,Supra awg 13 ,and 15 
is a Huge upgrade then the Coincident Wire at less then $3 a ft Madisound.

Agree with advice regarding the inductors, you can easily degrade the sound quality if not sure of specific specifications. Thread carefully. 

Don't agree with advice to rewire as the internal Coincident wire is very good quality. 

Brownsfan (Bill) nice approach for your tweeter capacitor. Some folks don't like to use bypass capacitors but happy this solution worked for you. I went Duelund CAST copper foil capacitors at the tweeter. 5 years later I remain  very pleased with the improvement. Did you consider changing the internal wiring? I sure didn't. 
Charles