Here is a comparison between x22i and x16rt, tested on the same rig (4 x R9 Nano, stock ROM, Win7, Crimson 16.3.2) with the same settings on the cards (900MHz/500MHz/-72mV) and the same settings in the miner (--opencl-threads 2 --opencl-launch=18x0). Total power draw for the entire rig is measured at the wall, i.e. includes CPU (70W in idle).

x22i gives a constant 5MH/s per GPU at constant 650W total power draw.
x16rt gives 6MH/s to 12MH/s per GPU at 500W to 800W total power draw.

With x16rt the power draw changes dramatically every time the hash order is changing. Consider this and use lower intensity to not run into the max current breaker of the PSU if your PSU isn't oversized.

For x22i wildrig-multi-0.14.0-beta was used.
For x16rt wildrig-0.15.0.8-beta was used.