The danger is with powders, not pills. Dosing powders requires you have a scale that is more accurate than what most people have, and proper technique in weighing it. The best way for most people to get an accurate dosage is to compound the caffeine with some filler and weigh that (cut it, basically).

Honestly, the only reason you should be dealing with powders is if you're making your own 'stack' of nootropics.