I agree with some of the other learned growers. You can get very good results using a MH all the way through. If you give them plenty of light Im not sure you suffer yield wise that much with a MH.
Yield and Quality is more connected with the genetics of the plant compared to the type of light it gets. Most of the MH bulbs you buy are full spectrum or close to full spectrum.
I use 3k or 4k MH bulbs exclusively and get good results.
There is nothing wrong with using HPS bulbs they work great too.
I just find it less trouble to use the same bulb all the way through. And find I get bushier plants using MH.
Just my opinion.
Good luck