I'm not sure about 53814 but 53813 is replacing a B7 so no reduction in capacity. The bus working likely does Express all day apart from the school contract so an E300 would not be preferred. Aberhill does at least one school in the morning which is worked by a B11 before going to Edinburgh.
was that the one which used to do K4- Kirkcaldy high school - Edinburgh peak? I doubt it does any all day service, since the cuts.
They could use one on the X55 which is much busier this year compared to last.
This week we have had various B7's, E300's (branded for the Perth 1 & 2) and a Megabus tri axle.
I doubt it since there having to add in more journeys, coaches are useless since there leaving people behide. E300 plenty of room even for standing.