Hi Sam !
Actually, Dr Defrancq does this at the same time of a Lefort 1 but only if a small amount of widening is required (like 2 or 3 mm not more).
If he proposed you a SARPE, then you may need more than 2 or 3 mm of expansion.
I read several studies about these two procedures and a SARPE is more stable than a 3 pieces Lefort 1. Moreover, with a 3 pieces Lefort 1, the risk of hemorragia and necrosis is majored (I don't know if this word exist in English "majoré"), higher.
If I were you, I'll go with a SARPE, without hesitation