Nice description Pete ha ha! But I know exactly what you mean, my R1 made that noise too. My mate knew if I'd passed his house from inside!
I can't comment on the noise being different on start up though Dan, it's been a long time since I've heard mine.
I don't think warm air would make a difference, the ambient temp isn't likely to change much in 10 mins or so. And a few degrees difference going in won't matter, it's going to be 100°C or so out the charger if you're on full chat. I do remember measuring ambient, compressor out, and inlet temps when I had the R1 run in. For about 20°C ambient, the inlet was always hovering around 30°C, even when nailing it. Which shows how efficient the standard intercooler is, and is why I didn't bother changing it.