Power tiers can be problematic, especially in high power games with a large number of players. The following rules can be used to simplify using different power tier skills during a game.
Unopposed rolls: A skill with a power tier above mundane always gains better results with a success on an unopposed roll than a mundane skill roll. For example, a scientist with a +4 science skill at mundane tier rolls a +4 for a skill check to analyze a chemical compound learns everything about the chemical. However, a scientist with a +1 science skill at the superhuman tier who rolls a +1 would gain approximately the same amount of info as the mundane scientist. GMs should reward players who use skills at higher power tiers by giving them better results than is normal.
Opposed rolls: A character with a higher power tier making an opposed roll against a lower power tier skill gains a flat +2 bonus per power tier in difference. Both characters still roll 4dF. No d6 dice replace fate dice. For example, a character with Stealth at superhuman tier gains a +4 bonus on his roll when trying to sneak by a character with mundane Alertness.