Originally Posted by
lazerzxr
Incorrect, that is a very simplistic way of looking at it. It is critical to reach when comparing frames. Reach is measured from the centre of the bottom bracket not the seat tube. Draw it out and you will see. It is possible to have two frames with the same horizontal top tube length and different reach due to head tube length.
Actually, you're still looking at it too simply. If you're setting up the bike to have the same handlebar height, you would then be making the effective head tube the same length. Whether you have that length in head tube or in spacers, it still continues backward at the same angle. But even if we assume for a moment that you would leave the handlebars at different heights, you're talking about a difference less than 5mm unless you have some crazy length head tube.
You gotta look at the entire bike set up, not just what the bare frame looks like on a piece of paper.
Anyway, that being said, your advice to the OP makes perfect sense to me.