It came up at the pub whether it was quicker for me (Brunswick Rd) to go via NEPN or main roads to Roseburn as it currently stands - bearing in mind the NEPN route is much longer.
I've looked up my historic data on Strava as I felt it useful.
Today: Home to Roseburn Bridge via York Pl, George St, NCN1 twiddles and West Coates: 4.7km 19 minutes. Pretty 'average' lights luck, some waits some roll throughs.
Previously: Home to Roseburn Bridge via Leith St, Princes St, Shandwick Pl and the 'bus and tram only' shortcut lane: 4.4km 17 minutes
Also Previously: Home to Roseburn Bridge via McDonald Rd and NEPN: 8.5km, 24 minutes.
So it's about 30% slower than the fastest route and 20% slower than the existing on road signposted route.
Comparing objectively Princes St to George St, I'll probably now choose taking the extra 2 minutes on that route vs the stress of riding along Princes St and around the Haymarket gyratory system.
Funny - It's improvements to that exact route this thread is discussing ;)