Sam Saint, Saint Samuel, or 5AM Saint, never figured what they're going on about. But it is, and has been for many years, my favourite of my tried published Brewdog recipes. Actually, the only Brewdog recipe I bother to make these days. The last one (the sixth), brewed in June 2021, kept me going until November though there were other creations to distract me last year. So certainly aged! "Lychee" dominates the hop flavours, though by the end it was, perhaps, getting a bit tired "hoppy-wise".
You did say darker; it's not particularly dark in my book (the recipe says 60EBC! That would be dark but it's more like 30EBC), and not "bitter" by Brewdog standards.
I stick fairly close to the recipe but fiddle with the quantities to get the targets (OG 1.050 and a moderate 30 IBU). It still needs about 3x the boil hops to get 30 IBU; their recipes never meet their own targets. But all the "end" hops were translated as "steep" hops (30-40 minutes at 85°C ± 5°C) and all the dry hops get stuffed into the fermenter after fermentation (a lot less hassle). Kegged 2 weeks after starting making it (from fermenter straight to keg) with no farting about with CO
2 transfers (though I always purge the headspace before sealing).
"BBC" pelleted hops mainly 'cos they have keeping qualities miles better than ordinary American hop offerings. The Amarillo hops are kept as "whole" to provide some filtering capability (Amarillo have much better storage capabilities compared to the "C" hops).
So, I can't suggest steep or dry hop, 'cos I do both anyway! But maybe you can take away something from my gabbling?