I don't find that. Did 190 miles on A & B roads on the Classic 500 yesterday - no bother "keeping up" & cetainly never felt "dangerous".
As this was the first run out after fitting the correct size tyres, I was running a GPS speedo app on my phone placed in the map pocket in a tank bag. The RE speedo appears to run 5mpg optimistic at all speeds & a GPS indicated 50-55 (55 - 60 on the speedo) is a comfortable cruising speed. 60 isn't a problem to the bike (it is actually smoother at 60 than 50), but as I don't have a screen it starts to become so for me.
The state of the roads your way may well be different to around here - extended 30 & 40 limits are the norm around habited areas, with main roads frequently downgraded to 50. Increasingly the 50 limits seem to be getting average speed monitoring. Having a bike that is comfortable to ride at those speeds is an advantage & far less frustrating than being on something which has a comfortable operating speed far higher than the limits.