I am not a plumber or installer but our house came with four wallmounts. I can only tell you that it's a nightmare. First, due to the fact that the carriers are bolted into the wood frame the toilets have sagged. Replacement was the next nightmare, we opted for floormount wall-discharge because they don't sag. It's a boutique market, VERY expensive, the available selection is very small and I found the quality to be subpar. It took six (!) toilet shipments to us until we had our first toilet that actually worked and didn't arrive in shards.
Long story short if I had the choice I would never, ever consider wallmount if I'd be building a new house. In fact if I ever needed to move and buy another house and it had wallmounts, I probably would not buy that house.
Europe has a lot of concealed tank toilets. Yeah, they look slick, I've lived there. But I remember that spare parts were rather expensive. You couldn't just take $20, waltz over to Ace Hardware and be done with it. However, they had less chlorine in the water so rubber and plastic parts lived a lot longer. It was quite normal for a toilet not to need anything other than cleaning for a decade or more.