A couple of points raised by the Cambrain Coast Track Plans.
The Cambrian Railways was always referred to in the plural, as it was a grouping of smaller Welsh Railways. It was in fact absorbed by the GWR just before the "grouping" of 1923.
I think you will find that the Cambrian Coast Express had seperate portions for the Aberystwyth and Pwllheli lines. These lines "split" at Dovey Junction, West of Machynlleth. (Possibly the portions "split" at Machynlleth, if not at Shrewsbury. I am not aware of the exact point.) I certainly cannot see the train running all the way to Aberystwyth, then retracing its steps to Machynlleth, before running through to Barmouth and Pwllheli.
While acknowledging the "Freelance" nature of the Porthmadoc plan, I do find it strange that the exchange sidings between the Cambrian Railways and the Ffestiniog have been ignored. There was at one time a large amount of trafffic handled at Minffordd. Coal, Explosives and all sorts of goods to Blanau Ffestiniog and the quarries, with slate the main outward traffic.
Kits are/were made for some of the Welsh Narrow Gauge locos (and some stock.) in 009, and have been for some time. (e.g. Peco.)
The list of locomotives suitable for the Cambrian Coast Line is missing the 45XX Small 2-6-2T Prairie Tank Locos. The Straight Topped Tank version is modelled by Bachmann, and the Slope Toppped Tank (Earlier) version was an old Lima Model (Available second hand, and maybe Hornby will release an improved version?).
Also missing is the Dean Goods 0-6-0 Tender Loco, which was, despite its name, used as a mixed traffic loco. The Dean Goods was a "Mainline" model, and is currently made by Hornby.
(Has Hornby Magazine got something against this loco, as it seems to have been ignored in a couple of "list" articles lately?)
I hope the above is useful.