scotts33 I agree, and this is where the hybrids are a key part of a Pinhawk SL set - they are much higher launching than the irons and therefore can replace a 6i, 5i, or 4i if the player doesn't have enough clubhead speed to get those clubs up in the air high enough at 7i length. The guideline that I have come up with for my fittings are:
85mph+ = enough clubhead speed to hit all the way down to a #4 iron
80-85mph = #4 hybrid
75-80mph = #4-5 hybrids
70-75mph = No #4 at all, #5 hybrid
65-70mph = No #4 at all, #5-6 hybrids
60-65mph = No #4 or 5, #6 hybrid
55-60mph = No #4 or 5, #6-7 hybrids
<55mph = consider the all-hybrid set, and possibly even just get every other club (ie. 6, 8, PW, SW)
Again, this is just a GENERAL guideline that I have developed over fitting hundreds of golfers for SL irons. Obviously things like AoA, ball placement, face angle at impact, and even shaft choice, can come into play which can make a particular player launch the ball higher or lower than normal for a given swing speed. But it's a good starting point.