RTM said:
it all depends on that all-important imaginary line from your knee to your forward pedal axle when the pedals are in the horizontal position. at 6'3" with a straight seatpost I'd bet you are tall enough that your knee hangs over the pedal, in which case a layback seatpost would be perfect. of course, once that knee angle is right either with a straight or layback post you're done there and the stem is your best bet.
I think "imaginary" is the key word. I remember learning the rule of thumb you are speaking of, but I wonder how much it still applies. Over the past few years frame geometries (as well as rider position) have gone through some real changes. Handlebars are often much higher and wider than a few years ago. I think cockpits are generally shorter as well. There is a big difference between a racing/xc setup and an all mountain/trail setup.
I have my road bike set up excactly as you suggest with regard to seat/knee/pedal placement, and my earlier mountain bikes were close, but as my bikes have become more all mountain in build and riding style, that seat has kept moving back relative to the pedals. I recently built a SS and I notice I do like the seat more forward, but not like the road bike.
I guess my point here is that I think that rule of thumb is a good one to keep in mind, especially in road bike and racing/xc setups, but there are good reasons to consider deviating from it for other setups(besides getting a small frame to fit).
I'm no expert in this field, I just know what works for me. I have so-so knees and seat placement is pretty key for the comfort of my knees, and I have found that moving it back is OK as long as I keep the seat height correct. Of course if there is some physiological reason to keep the seat where you suggest, (such as it generally being harmful to deviate from this) then don' tlisten to me. However, I have never heard of recumbant bikes being harmful.
