I have both, not because I am a pro, because I am def. not but because I like stuff like that, learning it, etc. CS5 is more powerful and I use it for things LR3 cannot do, but having LR3 to manage my images (I only have about 6000 right now - all excellent quality of course) and LR3 being much easier to apply standard edits to all at once, be much easier to work with regarding minor touch ups like you mentioned, etc I like having both.
If you have the money (I mean like really actually have it - not the credit or the pay yourself back method) it makes no sense to get less than you can have IF you are going to use it. I'm not saying throw your money away, just that I find they both have their useful places even among amateurs like me.