Rob,
I don't own a chrono, never saw the need. However, many customers of mine have stated over the years that they are really surprised how fast my bows are, from 45 - 80 pounds. They are ordering bows that are comparable with the weights they were currently shooting and are comparing arrow speeds with bows that are reflexed or straight. Most customers are shooting arrows at least as stiff or in many, many cases they are shooting arrows stiffer than they are used to in their other 'hill style' bows. I think that if the bow is tillered and timed properly, it will shoot well regardless of the weight.
To clarify my previous statement (not to put anyone down, especially other bowyers of whom I send many customers) I believe that Hill's bowmaking principles have been lost on many people. Hill also was constantly tinkering with his bows to make them better while still keeping their original form and function. A good string follow bow shouldn't follow the lead of a backset bow...they are different bows and should have different design attributes, while still conforming to Hill's original principles. This means that a good string follow bow can shoot very comparable with a straight or slightly backset bow for speed, but be much better in terms of shootability. These are my thoughts on the subject based on years of research and bowmaking and aren't in any way meant to demean anyone's bows or bowmaking abilities. I for one am over the top excited to see such an interest in Straight End longbows, and the renaissance of their popularity. I have limited bowmaking time available and therefore send many potential customers to Miller, Ekin, and Turay who in the past few years have enjoyed the resurgence in string follow design, carmelized bamboo, and visible-fadeout risers.