With regards to decoder sizes, I hard-wired a Digitrax DZ126 into my Dodo last night and the size of it is ideal. Unfortunately I can't give you a recommendation for it though, as despite the installation seeming straighforward, I seem to have cooked it. The loco only ran for about a minute before refusing to respond to demands to move or accept/tell me CV values on the programming track. As I've replaced all the wiring and it's all got to come back out again, I'll probably fit a 6 pin harness for the next decoder to just plug into, and that'll have the bonus of giving me convenient test points for my wiring instead of just a wodge of shrink-wrap that has to be cut back to reach the PCB.
Needless to say, I'm now even more annoyed with Hornby coming up with their non-standard 4-pin answer to the question of DCC fitment for the Sentinel and Peckett than I was before the latter was released! I'm not sure that Hornby understand that DCC uses accepted standards for a reason; any other manufacturer would have put a 6-pin decoder socket in (and produced or rebadged their own decoder to suit), and it'd have taken 5 minutes to fit a decoder of my choice instead of a good portion of an evening. It seems particularly farcical given that I believe X9659 is currently in short supply.
Decoder woes aside, the loco is lovely and runs beautifully on DC. It's one of those dangerous additions to a collection that gets your mind wandering towards entirely different layout plans to what would suit the rest of your stock best...
