I think you shouldn't be discouraged with your latest experience, it was just coincidence of some factors which are unlikely you happen again, so, when you are ready I think you can try to get some more of these fluffy balls.
I also think that if you strongly believe in free whelping and you had 4 perfect ones, you shouldn't be scared to do it again. I am sure that with the help of your vet you can always succeed.
Personally I am a human doctor, so I believe in medicine and have no problem with CS. I think that most of the risks of SC are very predictable and therefore if they develop, you can address them quickly and effectively. Natural labour risks occur suddenly and not always you know immediately for sure what is wrong, and it takes time sometimes to diagnose and address them, what can cost some baby lives. But, again, it is may be just because I know too much about medicine and always think of possible complications

Btw, when I had my daughter (she is 13 now), I started to bleed at 8 month pregnant. Doctors tried to keep the pregnancy for 1 day, but it didn't help and they said that we have to deliver her. I used to have very bad eyesight with retina damage, so from the very beginning of my pregnancy I was recommended scheduled CS. But, when that bleeding started and treatment didn't help, doctors told me "ah, baby is just 2 kilos, may be let's go into labour, it will be quick and easy". But I was too scared to lose some more vision, so I chose CS. I was selfish at that moment, frankly speaking. When my girl was delivered, it turned out, that she already suffered for some time from lack of oxygen and tried to breath inside, and aspirated some waters. She had severe pneumonia because of waters inhalation and was on supported breathing for 1 MONTH. Doctors frankly told me - if I chose natural labour, she would be dead in process, or would be born with severe brain damage due to lack of oxygen. Since then I celebrate my bad sight like a gift of destiny that kept my daughter alive and well.
For me CS worked magic. At the same time, I have huge respect for women and female dogs that give birth naturally and take pride in it. I think that you must first take some rest after your and Diamond's ordeal, and then go with your gut - to breed or not to breed, CS or natural birth.