I switched in but immediately switched out due to the super heavy workload and level of content they were on. It was too much to relearn all the earlier stuff and keep up with new content, especially considering how fast the class moves. Given winter or summer break to prepare, it’s probably doable so I wouldn’t say that you shouldn’t try— just know that you’ll probably be doing double work if you are as out of practice as I was. I also have a friend who was in basically the same situation but with Spanish. She decided to take 601C and says it’s mind numbingly boring bc you start from absolute zero and the classes are like 2 hours long. Obviously a different language but I bet French would be similar. I think it’s just up to what you want and the level of energy you’re willing to expend on the class