Dan in my opinion if enough rigidity can be acheived the actual positioning of the struts is really not important. If the float position itself i.e. incidence, distance of the floats apart, step/CG relationship and both parallel are all approriate then the airplane will be a delight. Even a low powered and heavy airplane can be a joy on the water with float positioning being the key.

The only possible disadvantage I can see with front struts a bit far behind the middle of the float would be a bit flexible or in the case of a very hard landing possibly float damage.

John