No offence, but (usually said by those who tend to offend) the 800 class were a waste of resources given their limited usefulness and smack of a vanity project. As far as I can see built for just one purpose, to start out of Cork without a pilot.
Perhaps with a bit more thought, the J15 Nua class could have been improved from the disappointments they turned out to be? A Jeep-like loco would have been an ideal, go most anywhere loco, but unlike today there was no shortage of operational turntables for tender engines.
OHLE was tried and trusted by the 20s and 30s, perhaps that could have been adopted for Dublin suburban rather than the Drumm units in a what if scenario?