Hopwood wasn't a project that I'd expected to build and as it was designed to meet a certain criteria (i.e. not mine) it falls short in a couple of respects. For home use the two road fiddle yard is probably adequate, however for exhibition use the expansion to three with a little track-end isolating opens it up a little, but that's just about all you could do - lifting cassettes in and out of the FY space would be the only other option and to be quite honest I'm not a fan of waving whole trains around in mid-air.
Two Hopwood operating sessions have taken place with Nigel acting as extra brain and critic. Both of these have attempted to use loco hauled stock alongside the DMUs. The reason for trying to crack this is my desire to create a more prototypical railway operation. Not the 'add the extra siding to put the mail van in' beloved of the freelance narrow gaugers. That plays against my knowledge of actual operation and of human nature. This is more a correct sense of purpose. When modellers say 'operation' what they really mean is extra places to put things to create more (and often superfluous) shunting moves. I'm tempted here to quote Cyril Freezer's comments on boring layouts, but I'll let you look that up. We are now surrounded by unit stock on the real thing which essentially act like trams - running from A-B and back again. The steam-age, and to a slight extent up to 1980s diesel- hauled operation, works a lot differently; trains being joined and separated, extra coaches added, slip coaches in earlier times, tail traffic on push-pull and autotrains etc. etc.
In my research(!) for the Southern book to your right I read whole tracts on why the SR pushed for electrification. One reason was tram competition in South London, but more than that it was to tighten up the departure times so that there was for example an 08.15 to London from all the commuter-belt towns and that there would then be a 09.15 and 10.15. Beforehand the timetables had been much more random due to...(and this is the bit we want) loco watering, joining sets of carriages, addition of extra bolstering stock and removal of the train engine to be turned/fuelled/oiled and replaced by a fresh one.
My interest in this has been heightened by viewing John Elliot's videos of his (now sold) Bradfield Gloucester Square. There's a link at the bottom and I recommend that you pour yourself something warming and watch through the entire lot. This visually demonstrates the above and this is definitely something that I'm slowly aiming for, at least in my head anyway.