The Road Hole has lost some of its teeth due to technology, whereas I think in some ways Carnoustie's 18th may be tougher because of it, because it is now harder for people to play it as a three shotter when conditions indicate that as the prudent option.
I'm probably biased though because my misses are almost all left, so I can aim right of the 'o' in Hotel with a driver and not fear the shot nearly so much as hitting an approach shot into the wind on Carnoustie's 18th with that OB lurking nearby (I came within a couple feet of that fence last time I played there, which I'll probably remember next time I play that hole!) On the other hand, I've always done very well at Carnoustie, especially on the last three holes (playing them at -2 the first time, and at even the second) and always underperformed at TOC, so who knows?
Assuming one doesn't slice the drive, you aren't likely to incur penalty strokes on the Road Hole, and the road itself is easy enough to play from. You just have to stay out of one bunker and you likely won't do worse than a 5 or maybe a 6 if you biff a short putt. You can shoot almost any number on Carnoustie's 18th because between the burn and OB potentially in play on every shot until you are in spitting distance of the green, you could reach double digits if your swing and senses happen to desert you on the tee.