We got a gold last time too, and I’m not sure that was followed by increased investment and new facilities – the only new facility since then was the one at Glasgow, though that I think is a Commonwealth Games legacy project and given the build timescales doubtless the funding was in place well before 2012. Though quite a bit has been built before that – most obviously Lea Valley, though Cardiff wasn’t much before that.
Plenty of summer whitewater in Scotland – I’m fairly sure I raced at Grandtully in August or September (though I do also remember it snowing there in April). How old are you though, because artificial courses which run in summer are nothing new – the first here was the Trywerwyn which was developed for the 1981 world championships. Also Nottingham which took over from that as the national centre until LV, Tees Barrage and a smaller one at Cardington – Washburn is a natural river, but still dam release so can run in summer too, I’d be surprised if there aren’t similar sites to that in Scotland I don’t know about.