I think you're right, my first run with a CMH was using a 600w until halfway through flower and switching out for the CMH toward the end, got far superior yields than with either alone. Some people do switch from HPS to metal halide towards the end of flowering anyway, I can only imagine the CMH is slightly better than that.A 315 cmh has no where near the coverage and intensity of a 1000 watt hid.
I have the sun system and a Phillips 3100k and I do really like it but it doesn't even compete with my 600 Hortilux Super hps either. Lotta hype that distracts the buyer from the small coverage area with high gram per watt claims.
It covers 2.5 to 3 feet square for flowering. I will use it only as supplemental spectrum to my 600 hps until I can try 3 in place of my 2 600's.
I have found it has the power of maybe 450-500 watt hps but only the coverage area of a 400.
I do really like the natural looking light to work in.
It also is as hot as my air cooled 600 hps but in an open reflector. I did need to add ventilation for it.
Seems growers with multiple overlapping lights are seeing the benefit as a stand alone lamp more to me.
It does increase resin production, frost and color over the hps. And some strains are finishing faster. I really like them paired with the 600.
I have been trying to figure out how to fit it in between my 2 600's. That would add the perfect amount of blue light for flowering and a little uv. If I went with the 4200k bulb even more uv. Even some uvb.
I'll save my reservations until I do a full run of 630w CMH myself and compare that to my HPS. But my HPS yield with autos is still way off my CMH photos right now.