The only thing I can imagine they might be offering is redis that scales without the drawbacks of the official redis cluster sharding. I don't know if that is

The only thing I can imagine they might be offering is redis that scales without the drawbacks of the official redis cluster sharding. I don't know if that is what they're doing, but it's one possible thing they could be doing "better" (as in its an area that could be improved, not necessarily that it's fundamentally or technically possible/easy)