Long midface is tough to fix, but if it's mild, it's likely not half as bad of a problem one might assume.
It's hard to tell without seeing your entire face, as I have no idea what your ramus looks like or how your bite aligns and harmonizes with the rest of your face. In your situation, I PERSONALLY probably wouldn't go for just an implant/genio since your whole lower lip appears to sit behind the upper lip. If you had perfect occlusion with just a receded chin, I might be inclined to suggest otherwise.
I'm not sure I understand your last paragraph - are you suggesting you already had braces? If so, do you need decompensation? If you do need decompensation, yes, you will temporarily look worse, but the jaw surgery will almost certainly look better in the long run since you'll just be getting braces again after anyway.
If you mean you're just worried in general that jaw surgery will hurt your aesthetics, I mean... surgery always has that inherent risk, but the lower third looks better with more projection like 90% of the time imo. If it's a simple BSSO + genio, and as long as you pick a surgeon who actually knows something about aesthetics and isn't just concerned with functionality, I think you have a lot less of a chance to go wrong.