Thanks for that - that is very re-assuring - you have helped me make the decision
I was originally planning to just upgrade the local disks from 10K to 15K SAS with enhanced cache, but that was going to cost £1500 (~$2,500) anyway, but I can upgrade with enterprise level HP SATA SSD discs for about twice that. However that would seem false economy going for the SAS disks given huge diference in performance I'm expecting from using SSD.