I would have to agree with Jubber on this and say we cannot really make that decision for you. I would say stay with a few accounts and slowly build on more if you find yourself enjoying it. I originally played only one account for ages, added a second to see if I would like it and then finally hit five late last year. I might hit wife aggro, which no defense rating will protect me from, if I try to add anymore so 5 will have to stay my limit. The point being is it might be wise to start small and toy around with the different race/class mechanics. If you find yourself really enjoying it and would like to dabble with more go for it. The time thing should not be an issue as once you have higher level toons you can just boost them quick enough through instances. However, I have seen a post somewhere that gave a rundown of maximizing your RAF time. I would do a quick search for that if you are really interested in that asapect.

Hope that kind of helps you