I had the same question! Now that I added Talyllyn to my Skarloey engines, running them on N Scale track is bothering me!
That same Peco starter set is available on Trainworld here in the States too. I was worried if the radius might be too tight, but I assume all the Bachmann Skarloey engines work fine on your layout.

Hey all! New to the forums, I thought I'd join in the discussion!

The best choice for Bachmann to make after Daisy is... Bear! He shares the same chassis as CGI/RWS Daisy - being a BoBo!

Kidding aside, my pick for the next diesel is BoCo. My collection mostly sticks to Season 1-4, since I grew up with those and the RWS. If we get Stepney then BoCo, we have the full standard gauge roster! (Minus Class 40, but do you really want him? Dude doesn't even have a real name. ... I'd probably still buy him though.)

I also would really like a Diesel 10 too. I like the Warship basis and have even considered getting a red one shipped from the UK and just say Diesel 10 got a repaint and lost his claw.
Regarding his claw, did you know D10 appears in a book, "Diesel 10 Means Trouble", and early concept art without it? It was supposed to pop out of his roof. I don't know how practical it is, but it would be cool if Bachmann was able to make that work without ugly seam lines when running without the claw. Or maybe have like a small, weak, magnet glued inside the roof? Weak enough to not affect the motor, naturally.

Also, regarding Stepney being next, I do have a question. Correct me if I'm wrong, but didn't Hornby and Dapol (or was it another UK company?) make Terriers last year and noticeable NOT a Stepney? I expect Stepney to be an easy cash grab in a Terrier range, being one of the first standard gauge UK steam engines preserved and the T&F popularity, despite being faceless.
So, I'm wondering if there's some sort of licensing needed from the Bluebell, and maybe they got protective after Alcroft tried suing them for running Stepney in the 90s for looking like a T&F character (despite real Stepney being first), or maybe they aren't letting merchandise being made, as real-Stepney currently isn't running due to needing an extensive overhaul.