When you think about the concept of a set of irons that are all the same length both advantages and disadvantages become apparent.

Advantages

1.  Because each iron is the same length (roughly equivalent to a 7 iron)  your set up position will be the same with each club in the set.  You will be standing the same distance from the ball with each club.  The ball position (forward or back in relation to your feet) will be the same for each club.
2. Because all clubs in the set are the same length and have the same lie angle your swing plane will be identical for each club.  With conventional clubs the swing plane with the short irons is more upright (than a 7 iron) and more flat with the longer irons. Theoretically it is easier to master one swing plane than multiple swing planes.
3. As the shafts are all the same length and the heads all weigh the same each club will have an identical shaft flex and  swing weight.
4. MOI (moment of inertia) will be identical for each club.
5. The bounce angle and offset for each club is identical (with the exception of the sand wedge).

Disadvantages

1. Because each club is the same length and the heads are all the same weight your swing with the 8 iron through lob wedge (which are longer than a conventional set) will be faster and the ball will go further.
2. With the 3-6 irons (which are shorter than a conventional set) your swing speed will be slower and the ball will not go as far.
3. It may be difficult to achieve the traditional 10 yard ‘gap’ between clubs.

In a subsequent post I will examine the impact of club length on swing speed (and distance), as well as the effect of club loft on distance with a view to eliminating the two ‘disadvantages’ to single length irons.