I use both Flamethrower and Fire Blast on the Scarf set, as they hit different things. Flamethrower already OHKOs Bisharp, Ferrothorn, Scizor (wouldn't wanna miss and have it X-Scissor you), and weakened Mawiles, while Fire Blast hits healthier Mawiles, Amoonguss, and Venusaur out of sun. I haven't missed U-Turn on it.I feel that there is little-to-no reason to run Flamethrower on the scarf set. I'd remove the slash but leave it in moves (you already stated why it is inferior to Fire Blast). However, on the main set, state that is should always be used if you are running LO as it actually does KO standard Ferrothorn (252 SpA Life Orb Hydreigon Flamethrower vs. 252 HP / 52 SpD Ferrothorn: 224-265 (123.7 - 146.4%) -- guaranteed OHKO). I'd also remove the mention of Modest on the main set as it is too slow without scarf or a boost. Leave it for set details. I'd personally dash Fire Blast after Flamethrower on the main set, if only to 'align' it with Life Orb, making it obvious as to which move to use with each item.
Edit: Change the header of the scarf set to "Choice Scarf". It is mainly to make it obvious for people looking through the sets and what you have atm isn't very clear.