I echo everyone else that Painswick 1 is too much uphill. If the fairway weren't maintained as rough, the ball would just roll back to your feet.
Although I didn't mind it, the par 3 5th hole at Sage Run in the upper peninsula of Michigan is probably too steep for most. I couldn't get the elevation from Google Earth because the course is only a few years old and they don't show it yet. It must be 50 feet from the ~185 back tees. But of all the holes that I've played, it was the one that reminded me most of the 1st at Painswick in the severity of the slope. The short par 4 sixteenth is also very steep (plays up the same hill as 5), but they've blasted the hill to make tiers of fairway that allow you to work your way up it.
The 1st at Painswick:
The 5th at Sage Run:
And the 16th at Sage Run:
I'd also add as an honorable mention the par 3 16th at Hankley Common which I didn't think was so severely uphill, but I played behind a group of ladies who thought otherwise. The ladies tee was at the base of the hill and from here, the hill was steep enough that the ladies couldn't get enough elevation on their shots to carry it. The distance wouldn't have been a problem on its own. They devised a clever solution; the first one hit and then moved halfway up the hill to spot the rest of the balls as they landed halfway up the hill in the heather.
This raises a further point: 'how much elevation is too much' depends on who's playing. From forward tees, very little but abrupt elevation can be too much because those who play from there can't get the elevation on their shots. But for a low handicap, even these steep uphill shots are manageable. I think that steep uphill shots like the 5th at Sage Run are great for lower handicaps because they require good decision making (how much yardage to add) and, more than usual, that you hit the ball solidly.
The problem is that if the hole is really uphill from the back tees, you probably won't be able to locate forward tees in a place where it also isn't very uphill. If you could, that'd be the answer. Of course you could also reduce severity for those who can't get the elevation on their shots by not doing things like having heather between the tee and green, like they do on the 16th at Hankley Common.
The 16th at Hankley Common: