DXU-31, not IXU-31. IXU is ONLY used in the micro base.
RBS2216 can only handle 12 TRX in one cabinet, but it support a double cabinets stacking on top of each other, and that could have 24 TRX in the same footprint of RBS2206.
DRU is so compacted, so it can never as flexible as dTRU with CDU+CXU, which means the jumper cabling could be considered when you try some strange SCC.
But basically I like it since it is my babe….