Cleaning is pretty easy, as long as you don't expect the oven to ever look factory new. My oven cavity has a couple of minor but permanent stains. Doesn't bother me at all, but I just want to make sure to set the right expectations.
As for plumbed vs non-plumbed, we deliberately chose the plumbed model and we are very happy with this choice. It makes it so much more likely that I'll add steam every single time, rather than skipping it, because I am too lazy to refill the water. Also, it allows me to cook things that take a long time. The CSO has very precise temperature control and thus makes for a very convenient alternative to an immersion boiler for sous vide cooking. But that can take many hours of cook time, and with a water container you have to worry about refilling ti.
I do understand the concern about water leaks though. Realistically, it's no different from ice makers, dishwashers, and other appliances. These don't fail frequently, but they do occasionally spring leaks. And that's why we put a drain pan underneath the CSO. It drains into the same pipe that the oven drains into. Hopefully, we'll never need that feature. But it does give me peace of mind, and my contractor didn't think it was all that difficult to add into our cabinet.
Q
Again, this one is just like mine.
Q