Some when in the Summer of 2016 I realised Shelf Island should be an H0 layout, with occasional 00 visitors, instead of the rather vague "00/H0 avoiding scale models near the lineside". The tipping point was reworking the Fleischmann Warship and getting a really nice-looking model ... and the realisation I possess more H0 wagons and coaches than I every owned in 00.
The loading gauge will stay large enough to accept a Hornby BR Mark 3 coach, but not a Rapido APT-E. This lets the layout fulfil its original purpose, which was a playground for my collection of 00 gauge shunters, and also lets me indulge in occasional out-of-gauge Continental items like this pair of steel carriers in a non-prototypical but rather appealing livery:
If I had any sense I might be an EM modeller - I enjoy altering RTR models and I like the look of EM. But I want to keep the interoperability with 16.5 mm track so I can run on other layouts and set out an oval of track from time to time. I'm unhappy with the appearance of 00 gauge and I expect some of my H0 models will end up a bit too wide, but at the end of the day I'd rather have the majority of my models looking right on the track, and accept a few outside cylinders jutting out here and there if the need arises.
It has taken me 35 years to get here. It follows an essentially H0 scale British layout I built in the early 1980s, where I relied on a Mainline J72 (small prototype) to "look right" but no actual 1:87 scale trains; and then some British 1:87 narrow gauge in "Castell y Bwrdd". The Internet is a huge help here, because the most innocuous enquiries to so many model railway dealers bring blank responses.
As a by-product, the available RTR in H0 scale is directing me towards the Southern Railway and its successor in BR. This is no bad thing for a modeller who likes just about everything "railway" and could do with a little focus in his efforts; and I have family connections to Hampshire. So although Shelf Island is an imaginary location, its next extension could be a Southern prototype or might-have-been, with the possibility of a British exhibition layout in H0 scale - which would be a nice break from the mould.
The other immediate benefit is space. A layout designed for 00 suddenly looks more spacious with H0 trains. I like H0 for British subjects, I like it more than any other scale/gauge combination, but I've had to try it out to realise this.