How big of a no no is HPS light for veg stage?

I have a 100 watt HPS light for my tiny grow box I'm only raising one plant in. I just saw this chart

Lighting Selector Chart

That makes me really think I should invest in a metal halide light for the veg stage and swap it out for the flowering. Damn, this might make me just buy another container and have a metal halide one for veg and I could just swap it over to my hps for the flowering...

lots of people grow exclusively with HPS... they'll probably just stretch a bit more and not grow quite as quick compared to if you had a MH to swap