You may be surprised, but I'm not terribly so - and by the way, congrats! A well-designed modern coated lens on a fixed-lens rangefinder *should* be capable of better results than even a high-quality zoom lens; a lens which, although very good and very well-designed, still represents a series of compromises that a prime focal length does not.
The drawbacks in comparison of your SLR to the Yashica are many - you would not want to ditch the Canon and go with the Yashica for every photo. BUT, used within it's range of capability, it should beat the pants off of just about about anything that is a 'compromise' that tries to do many things well instead of one thing superbly.
I find the Yashica Electro GSN lens better than the Canonet - I know some disagree with me - and I'm a 'Canon Guy'. I like the Minolta Hi-Matic 7S and 9 lens about as well - and the Minolta has a manual shutter speed that the Yashica lacks. But the Electro is a FINE machine, no doubt about it!
Anyway, I wax poetic over this stuff and then I get boring. Congrats and enjoy! Post some scans!
Best Regards,
Bill Mattocks