Answering just the OP:
I don't feel too much guilt for going to a breeder for my current dog. Breeder vs. rescue was not even a deliberately made decision for me this time around. I put word out that I was mainly looking for a stock dog breed or mix (cur or herder), and preferably out of working parents. There are individuals of breeds/mixes that I would have readily accepted coming from a shelter, but I found my dog's litter first, was able to watch his dam work, and just generally approved of her temperament.
I would like to take a dog from a shelter in the future, although whether I do will depend on what breed(s) I decide I'm most interested in. Another Catahoula, for instance, I would probably seek out a breeder for, because what I like to see in curs is well-rounded farm dog temperament, a good balanced mix of herder-like, hound-like and molosser-like or for smaller curs terrier-like qualities. Currently, enough Catahoulas are being bred to emphasize hunting and baying instincts over stock sense and/or or are being trained early on penned hogs, that it might be difficult for me to find the herding instinct I want in a Catahoula from a shelter. Or else I might run into stock dog training issues caused by early training of the then-future hawg dawg that was designed to encourage unchecked prey drive. (Notably not a big problem with my dog now - he gets excited to be sure, wants to work close and prefers high-pressure to low-pressure situations, but no signs yet that he won't be able to adjust his approach to sheep if that's what I ask.)
Kelpies, ACDs, Aussies, BCs, Lacys and mixes of those I might be more able to take from a shelter and still feel reasonably confident that the dog and I would mesh.
I do feel slightly more guilt for buying from the breeder I bought from, although not enough to seriously regret it, as he's grown into a healthy, promising dog. She was a bit of a line-skirter responsibility-wise. Not a Puppy Mill BYB or anything - she was breeding puppies out of sound, reasonably aged working dogs to sell to people who had shown interest in her dogs' working abilities, on a limited basis, and was not at all making much money from it - but still not as thorough as I would look for in the future, either. (Not that she is breeding anymore - two litters were her limit.)
I would have preferred to have seen a somewhat more serious screening, more/better parental health certifications, and most of all a program that included genetic testing for merle or at least excluded obvious merle/merle breeding. (I excused her enough to do business because according to known research Catahoulas are less likely to produce double merle dogs with serious impairments. Case in point, my dog is double merle and has no serious associated medical abnormalities to speak of. Many more reputable Catahoula breeders also do merle/merle, so the example being set for small-timers is conflicted.)
So overall, I'm alright with my choices even if I could have made even better ones. I got a good dog. I would like to take a dog from a shelter but whether I will is very situationally dependent.