CNA is cake I took it with A&P II with no problems, did great in both. My friend is taking A&PII, Microbiology, Intro to Psy, CLEPing Comp I, and did the CNA...I'm not sure what she was thinking when she signed up but she's doing great in all her classes and just finished the CNA last week. It is absolutely do able. Just make sure you make time everyday to study and you will do fine. CNA classes usually only last 6 weeks and it's mostly common sense stuff. Once you practice the skills enough in class they become second nature.
I don't know if I'll change my tune toward the end of the semester but I'm in A&P 1 right now and preparing for our second test. There is a lot of memorization but I don't find the class to be hard. I work 50+ hours/week, able to study and have free time to do other things right now. It really depends on the student though. Some people will struggle with the memorization. I thought I would because I'm no longer a young 20ish year old but I can still recall things fine it seems with enough repetition.