do I REALLY have to switch to HPS bulb for flowering?

I mean metal halide is a full-spectrum, uv-outputting, noon-day sun mimicking complete balanced RGB=white light spectrum. What plant wouldn't want a noon-day full sun spectrum for flowering? ...over a yellow-red spectrum that is not a balanced spectrum? The sky does not turn yellow and murky like a nuclear holocaust all day in the fall...hrmm...

the sun indeed is mroe to the yellow red spectrum in autumn thats why leaves change their colors and thats why marijuana loves that for flowering as it starts to signal for the end of life and to produce flowers/buds.

No you don't have to do anything bro, hps puts out more lumens per watt and are better spectrum for flowering.
She will still bud with mh, or cfls

no, you don't have to switch to hps for flower, and in fact, my last grow was my first from seed to harvest using striclty mh's for the reasons you've stated above, but mostly for the increased uv output that mh's have...
i was happy with the results, and will be using strictly for this grow again.. i use sun pulse mh's that come in various k ratings from 3k to 10k, and you simply use the correct k for the phase of growth you're on, ie, 6k for veg, and the 3k for flowering, etc..

there are expensive new ones with mh and hps in the same bulb. it would be cool to set both side by side with some overlap between. I just gotta get my studfinder and move a couple hooks.

If you have to pick one....go with HPS, lots more lumans per watt.

wassup bro. like evryone els said your plants will do fine under an Mh even under cfls to be honest but in all reality in order for your plants to really thrive and produce. ur plant will love you if you switch also ur buds will come out more dense and rock hard not fluffy or airy.also your yeild will increase and trust me you will be able to notice the diffrence. it will be best to get the hps and in the end it will pay for it self. but most of all your plants will love it. keep it green and keep growin

No，You will regret it.