Sorry about the slow response; I just saw this post.
I've never used injectable SD (or any other injectable methylated AAS, aside from Anadrol and D-bol), so my personal experiences are limited. Furthermore, I don't experience appetite suppression with most orals, regardless of the route of administration, so my response will be limited to what I have heard from others.
Like you, I have heard from quite a few others, including clients, that side effects were less pronounced when injecting methylated drugs, particularly in terms of appetite. However, some people have reported problems regardless, so it certainly isn't a cure-all for everyone.
My guess is that it does diminish this side effect for most--not necessarily eliminate, but at least reduce it. Orals can mess with the appetite in multiple ways. Digestive issues (not everyone experiences this with orals) are eliminated with the injectable route, which can be helpful for some. We also know that liver stress can affect the appetite, which has been demonstrated in not just AAS users, but in others who suffer from serious liver issues as well (i.e. alcoholics, etc). Again, not everyone has this problem, as I have seen innumerable instances of people with super high liver enzymes who haven't experienced any perceivable decrease in appetite. Obviously, by injecting a drug rather than swallowing it, we don't have to worry about these potential issues, so this is part of the reason why injecting a methylated drug can sometimes be easier on the appetite.
However, orals can also cause appetite issues for unknown reasons, which has nothing to do with digestion or liver health. This largely comes down to personal response. This is why some people can use certain orals and be fine, but others may cause problems, even when liver enzymes are similar. For example, I know one guy who can use Anadrol without any problems, but SD suppresses his appetite so bad he cannot eat more than a couple thousand calories per day. I also know another guy who is the exact opposite. So, even though we don't know the exact cause (there are multiple possibilities, but we can only speculate), it really comes down to how you respond to each oral individually. While certain orals are definitely more likely to cause appetite suppression from a general standpoint, the only way to be sure is to use them yourself and find out.