Honestly, a few of us went through something similar with the switching between cow's milk and soy, and the general feel was that soy formula can be a decent option when your little one's tummy is sensitive or recovering from repeated diarrhoea episodes, Mamil Soy does have nutrients formulated to support digestion, so it's not just a "lesser" option. Someone in my mum group mentioned that soy protein is generally gentler on the gut during recovery, which is why doctors sometimes suggest it even without a confirmed cow's milk allergy. That said, since your LO is already 2 and eating solids, the milk is more of a top-up than the main nutrition source, so as long as his diet is varied, the switch shouldn't be a big concern nutritionally. Do check with your PD or a dietitian though, just to be sure it suits his specific needs long-term!