The X98/99 is the Cinderella service. Have a look at the East Keswick Parish Council website for the details of the criticism from the Council. The Citaros are too wide for the X99. The pinch points in Linton and East Keswick will damage them, just like they did with the ADLs, which were wider than the Geminis and Streetdecks that First used.
The type of bus isn't the problem though, it's the unreliability, the constant late running, and the constantly changing route after Harehills, which does nothing to avoid the traffic. It should use the 36 route from Sheepscar, which has an uninterrupted bus lane along North Street, whereas Regent Street doesn't and is always jammed. First worked that out years ago at peak times. Transdev still haven't done so. It's also the speed of the service. It's just so slow. It isn't even a limited stop anymore, as it used to be under First.
It will probably return to First as part of a package of routes under franchising which is for the best. It was clearly a route that Alex Hornby wanted, at least as something to use the redundant CityZaps buses on, but he went, the Zaps went and it must be problem route for Transdev. Dead running, drivers to be shuttled to and from Wetherby on the just as unreliable 7, that basically only runs once per hour. There are no proper facilities in either Wetherby or Leeds Boar Lane for the drivers. The public lavatories close early in Wetherby. I have seen drivers use those in the bar by the stop at Boar Lane.
It's a service that is packed only in the evening peak from Leeds, and by the time it reaches Redhall, it is virtually empty. Few people use it regularly along the entirety of the route, because it is so slow, and because they are likely to own a car or several, because of the lack of alternatives and because after Redhall, the areas are very affluent. Linton has the most expensive house prices in the whole of Yorkshire.