The East coastway only has two trains, and only one variation for both trains (377/4 and 313/2) so I am suggesting more trains/variations first of all the 377/3. The 377/3 is pretty much the same as the class 377/4 with the main difference being the coaches. The 377/4 has 4 coaches while the 377/3 has 3 coaches. Next is the class 377/6 The class 377/6, again, is pretty much the same as the class 377/4 but with the two main differences being: 1. The coaches. The class 377/6 is a 5 car variant of the class 377/4. 2. The door tones The 377/6 has a different door tone for opening and closing, being the same as the class 387. And finally the class 387. The class 387 on the London commuter could be shown at Brighton (obviously only if you have the dlc) operating services to London Victoria.
The Class 377/3 and 377/6 would need interior modifications too, notably the removal of first class on one end of the /3, and use of the 'ironing board' seats on the /6. I'm not even sure the /6 is that commonly seen on ECW in real life anyway. In hindsight the Class 377/1 and /3 should have featured with ECW, the latter would have nicely substituted in for the 3-car Class 313. That would have been the best solution with BML containing the /2 and /4 subclasses, possibly the /6 and /7 at a stretch. Realistically though, there's probably not enough interest to model half a dozen subclasses for what is ultimately a very similar driving experience. I agree on adding Gatwick Express AI services at Brighton however. We also really need the Hastings/Eastbourne to London Victoria services added as well, the timetable does feel incomplete without them. Hopefully with some of the /1 subclass featuring in the recent BML, any update for ECW could include this allowing for the additional services using the extra units as a nice bonus.
It wouldn't really be that realistic to have such rolling stock you mentioned on ECW. While there's not as much variation, critically it's realistic to real life where you'll find the 313 on services to Lewes and down to Seaford while the bulk of the 377s are /1s and /4s, with the /2s also seen occasionally from time-to-time. Don't get me wrong, I'd love to see the 377/3, /6 and /7, but a more suitable route is needed, preferably one of Southern's Metro routes, which the rolling stock could then be included onto London Commuter. Saying that, over these I'd rather see the Class 455 as priority. Absolutely agree with your points here.
For 377/7 377/2 you're looking at WCML South since these run East Croydon Clapham Junction West London Line to Willesden Junction where they join WCML South to Milton Keynes. 377/7 377/2 run like 387/2 Dual voltage Third Rail Overhead wires therefore fast acceleration on AC power slower acceleration DC Third Rail. The American equivalent to them is the Metro-North M8 New Haven Line and in Germany the 474.3 490 S-Bahn Hamburg
