I have owned or heard both models & without a doubt the klf20 are the better speaker. Epics are great & if you asked about the cf3 vs klf20 i would say the cf3 is better or at least more equal to the klf20. 20's have dual 10" woofers, cf2 are dual 8" i believe, no comparison in bass or overall output.
Epics are a 2 way design & the klf20 are 3 way, some like 3 ways better than 2 ways but the mid/tweet horn/driver on the eipc cf3 & cf4 is much better than the mid on the klf's IMO, im not for sure but dont think the cf1 & cf2 horn/driver is the same as the cf3/4. A high quality 2 way is usually better than the average 3 way... look at the jubilee, its a 2 way & will embarrass any other 3 way klipsch speaker.
So basically, the 20's will be better than the cf2 in every way, if the price is right jump on them & then compare for yourself, can always sell the ones that lose or keep both.