I agree with MojoRisinSD's comments. However, one other consideration is the reliability of the software used to manage the two drives under Fusion. It is version 1.0 and it is a black box. If anything goes wrong you are totally reliant on a brand new software scheme. You will have greater speed and potentially greater reliability with the approach you mentioned but at higher cost. Another possible option is to combine a 760SSD with external USB 3 drive(s). You could also RAID two USB 3 drives and get a speed option very close to Thunderbolt. Thunderbolt drives are limited by the speed of the hard drives unless it is SSD based or or you are using a RAID enclosure in which case the cost is very high.