Johnny suggested using a FW800 to 400 adaptor to resolve how I could support clients FW400 drives if I went the e-sata route with my Mojo on the system.
Thanks for the thought, you are right but with an Avid Mojo on the system, my understanding is it takes the entire firewire buss both FW 800 and 400 so if you want to attach firewire drives you will need a PCI-e firewire card. However if I have fitted an e-sata card in my remaining slot then I won’t have the slot to fit a firewire card as well.
Johnny also suggested MaxDigital products as a more cost effective solution than replacing my removable drive system. 
I supply the MacPower Pleiades enclosures to clients and there is an equivalent 3 way case. I then put Seagate drives in them. Interesting you should point to Wiebetech, I have started supplying clients with their 2.5″ buss powered cases ToughTech, and I am very impressed with their quality.
My Intel machine is about to be fully loaded with drives, one system drive, one ‘storage drive’ which has all my sound effects, and two drives for Time Machine which I have set up to backup the system, storage and my two ‘external ‘work in progress’ drives. Thanks to Johnny for his excellent input. Folks please keep it coming as I hope this will helps other people in similar situations.
Hey Mike, You are right about the FW Bus Issue. The only experience I have with it is in our VO stage running it on the FW 400 port of an Intel machine and then recording to the internal SATA bus. Only note on the enclosure issue is that we tend to steer clear of enclosures with Wall wart or DC Supplies because of lost power adapters and the like. A box with an IEC C13 power cord gives us the most flexibility even if it does increase the cost a bit. Also the Maxx Digital boxes have a fan built in for cooling and a great controller board and chipset. I know many of our editors like products like Rocstor and OWC, but for our needs not having the fan and no IEC power connector was a deal breaker. Of course don’t even get me started on the garbage from Lacie, Ugh! We avoid anything from them like the plague!
Hi Jason,Thanks again for responding again. The Mojo thing is a pain but with the Intel Macs it is now one of the few ways of getting video out of an Intel Mac.Good point about the wall warts and external PSUs. I haven’t had any overheating problems with the Pleiades cases yet and although I have my drives away from the work area many of my clients don’t, so a quiet case without a fan is good news for them. For me the Macpower range are the best of the budget end of the market and you know you are getting a case with an Oxford chipset.Lacie… don’t get me started, cases failing, power supplies failing… Although to be fair they do seem to be making huge strides to improve their quality control and now offer longer warranty periods on their ‘professional’ products.Thanks again, Mike.