The resource cost when increasing the depth beyond the default value of 2 is similar to the resource cost of PIPOs. Namely, each increment of 1 will require enough memory for a block, e.g., in the example above N * 32-bit words.
The stream of blocks object can be bound to a specific RAM type, by
BIND_STORAGE pragma where the
stream-of-blocks is declared, for example in the top-level function. The stream of
blocks uses 2-port BRAM (
type=RAM_2P) by default.