Is system synergy worth having matched components?

No.

Most devices, like preamps, have an output impedance that is pretty low.
Most amps have a high input impedance.

if it sound good, then get more music and be happy.

@holmz : +1! Unlike gravity, synergy is an imaginary concept.

But am I doing myself a disservice by not even hearing the Odyssey Candela or Tempest preamp with the Khartago? 

No.

there are a LOT of members that mix and match equipment.

just as it was mentioned earlier, if it sounds good, then leave it , enjoy it and buy music to listen to.

I have had three "matched" systems over the years.   First was a Apt Holman pre and Apt 1 amp.... pretty good combo for a 17 year old kid.....   next was a McIntosh C15 and 7100...   again, not a bad system.    Third was a brand new McCormack RLD 1 and DNA 125.     The latter was oddly enough the worst "matching"  of them all.   

After about two years with the RLD 1 , I replaced it with a Conrad Johnson Classic 2SE.   That combo sounded great.    For what ever reason I could not warm up to the RLD 1 .   It wasn't bad but it didn't wow me like the CJ in that system.

The McCormack was sold and replaced with a pair or Quicksilver Mid Monos .  A fantastic pairing that. I have enjoyed for about 8 years.    

With respect to system synergy.... you don't know ya got it, til ya got it.

I'm still using the Quicksilvers,  but now driving them witha Zesto Leto.  The Leto is incredible,  it also demonstrated how great sounding the Quicksilvers are.

Those 2 components have synergy in spades.    Im having a 300b amp built, hopefully  it will play nice with the Zesto.    

if you are happy, you are happy...but might be fun to try the Odyssey preamps and some others...depends how much time you want to play around with...I've had great success both ways...