It might be ok for some all depending on tolerance to caffeine. I myself could never drink coffee while rolling. Coffee alone makes my heart pound and I'm speeding for a couple hours.
It gives you more energy. I'd suggest drinking the coffee before though ... on e it will taste terrible! And don't drink a whole cup. Just drink like half a cup or a "small". But yeah it gives you more energy. If you have pure m then it's actually fun to drink coffee before because then you've got the energy to dance and everything.