To nap or not to nap is not your biggest problem. Your 6 month old still waking 4 times a night is what you need to work on to get better rest for yourself (and in turn being an overall healthier person because of it.) With a good night's sleep for yourself, you won't need to nap during the day because you won't be dragging all day long.
Read Secrets of the Baby Whisperer -- start with jumping to the chapter in the back called "accidental parenting". It changed my life. Unfortunataley, I didn't discover this book until baby #3, so now I spread the word to as many tired moms as I can!!
A 6 month old does NOT need to eat 4 times during the night and is just waking out of habit and feels the need to use you (nursing, bottle, rocking, etc) to help him/her fall back to sleep. This book will teach you a very, very loving and humane way to teach your baby to sleep well.