(04 Mar 2020, 1:11 pm)streetdeckfan wrote I wouldn't necessarily say the B5s on the X9/X10 were a mistake, they're not doing that bad to be honest, for me the issue with them is more that they're absolutely awful to ride (engine noise, ride etc.)
I think the E400MMCs would be in a similar boat, going off my experience with the ones on the X30. Obviously without trying the Scania on the route (which they're trying to do) it's impossible to say whether it would be a better choice.

The issue with the route is that it's mostly motorway so needs a vehicle that can deal with that, but it also has urban sections which vehicles that would be preferred for motorway are traditionally pretty awful at!

Obviously there are other factors at play, but I'd suggest the fact that Transdev Blazefield have gone for E400MMCs for The Witch Way and CityZap over the B5TL is a good indication that operators really don't like the B5TL. 

That 6.7L Cummins engine is pretty reliable, and represents a 34% increase in engine size over the B5 - thus less stress on the engine at those higher speeds. If I remember correctly Transdev made a point about the reliability of the E400 running gear in their announcement of the order. 

I don't see too much of an issue, bar perhaps Eldon Square, for coaching stock on the X9/10 - remember that Megabus/National Express serve city centres and similar urban areas frequently with triaxle coaches without issue. The problem is more with accessibility, however the latest stuff from Plaxton addresses that very well. Stagecoach operate coach type stock on any number of routes within Scotland without issue.