Haven't been there in a while but would suspect that it has some pretty icy sections so caution is advised. You can also get up to some really good speeds on the descent and need to be watchful of the blind corners.
It is probably one of the gentlest climbs out of the valley but with that being said, I know that it is still a little challenging for some.
Finally got to try Groat as a commuting route & did not fair too well. I was able to maintain a fairly constant 50 KPH heading down but was still getting squeezed by traffic. I'm guessing the average vehicle speed to be around 65 or 70 KPH even though the limit is 50. That is well outside of my comfort zone. Didn't even attempt the uphill section, I'm too slow & wobbly. The MUT will do just fine.
Seriously... I could ride down Groat (proper) in excess of 60 kmh and still be overtaken by cars and it really rates as a stretch of road there is absolutely no need to take since the alternative route rocks.
I really don't think I would try that road at anytime other than the middle of the night with no cars. You are a brave person.
Not so brave as inexperienced. Looked at the posted limit at 50K & figured how bad could it be (a roadie bud told me it wasn't the best idea, but then what do they know???). Sixty Fiver pointed out the MUT & it has turned into a route I should have been using all along.