One more thought. Due to a quirk we have recently discussed, the held amount is more or less capped per node. However, each node has a separate cap. Therefore a SNO who has one large node effectively has less in held amount than a SNO who has many small nodes. I assume this was not an intention of held amount, yet should make SNOs who host many small nodes more careful when sharing infrastructure!
A single 20 TB node and 10 nodes of 2 TB each will, at current conditions, earn about 80 USD per month. Yet the single node will have about 8 USD in the held amount, and ten small nodes will have about 80 USD there. And adding the eleventh 2TB node will even increase that, making the escrow essentially linear in terms of storage.