No resinous benefit is seen from using mh for veg and hps for flower. The mh must be used late or all the way through flower. Though no scientific study has been published regarding the potency difference between those buds grown under mh or hps, many have observed a more resinous plant under mh or a combination of the two. Most believe it to be from possible uv production by the mh. It is quite apparent in those grows with stationary lights of mixed mhmand hps. Where the two intersect, there seems to be a sweet spot. When I grew commercialy, all my stash came from those sweet spots, closer to the mh side. It took a few grows to notice, but it was obvious to the point where they sometimes looked like different strains. As I grow small now, I use an hps until I start to flush and I switch to a warm mh. I found it drops my yield about 5% but makes it last me 25% longer. I don't own a gas-cromatograph mass-spectrometer but I'm pretty sure this method yields for me a more potent product. I get three extra rips off my vaporizer than with hps alone. Although these buds sometimes don't hold a candle to the cream of the crop, so to speak, of the dual light system I used to use. But I think my clones are tired so who knows. Homegrown organic jack herer still is better than %99 of the crud I've paid for.
I will be trying these new sunpulse bulbs available as hps with uv production on my next grow. Hopefully by Xmas there will be more info out there about their use with cannabis.