I would probably use other chemicals, if the cost-benefit balance was good enough:
1. Easy to acquire - even nicotine gum is a bother to buy, compared to the various teas, coffees, colas, or caffeine drinks within a few metres of my desk.
2. Valuable - there would need to be a positive economic benefit, otherwise it would be a recreational chemical.
To think like an economist, the 'positive economic benefit' would provide $-amounts for:
3. Quality of Life costs - a smart-drug which affects your sex-life (e.g. Adderall) or causes me to lose focus on my health will have a high negative value.
4. Long-term Health costs - similar to above, except this is more of an expected-cost for (the likelihood of it causing long-term health issues) * (the negative value of those health issues). Not usually very high, but as the article mentions, not many of these drugs have had conclusive efficacy trials, never mind long-term studies of their effects. This one really depend on your personal risk-aversion.