The downside of all of these instructions is the extremely low XO bit requirements:
2-3 bit XO due to the large immediates *and* the number of operands required.
The LUT3 instructions are already compacted down to "Overwrite" variants.
+(By contrast the Float-Load-Immediate instructions are a much larger XO because
+despite having 16-bit immediate only one Register Operand is needed).
+
Realistically these high-value instructions should be proposed in EXT2xx where
their XO cost does not overwhelm EXT0xx.