Hi thanks to all for your interest and answers..
I think you have a few different things going on here, so let's see if we can deal with them one by one.
I have not chosen the Mac-Pro because I have prefered wait FCP 64 bit version knowng that at this time the Mac Pro offer will be different
The current Mac Pro will run 64-bit applications. Macs have been 64-bit ready for a while, but you are right in saying that FCP is a 32-bit application. It is expected that it will be 64-bit RSN (real soon now

). The Mac Pro for sale then will be different to what is available now, but computers are always changing.
but I am glad to plan to buy one this year with thunderbolt expandability
If I had a Mac Pro right now, I wouldn't care about Thunderbolt that much. With a Mac Pro you can get up 4 internal drives that connect via SATA. Make those drives SSD and run a RAID 0 and you'll have
more than enough for full HD editing. It still has a display port and you can put in
eSATA for $25. You can also get pro capture cards that just plug in. I think Thunderbolt will have a bigger impact with laptops and iMacs.
Relating to XDCAM native.. I used the term native in two ways : native at its 35Mb/s and native with all of its MXF information that offers the crossplateforme of the clips that the quicktime's rewrapping prohib (except if you use the 99$ sony plug named cinemon)
FCP has handled XDCAM like this for
years so it has either been a problem for you for years, or you have changed workflow which makes it a problem. Whether or not that $899 Sony software is worth it, I would say depends on the rest of the system you have. Sony has flows involving playout servers and all sorts of expensive hardware.
Concerning the disks I use for work not for just storage (Storeva AluICE Extreme Quattro 3 To eSATA, x 2 + Iomega - UltraMax Plus - eSATA/FW800/FW400 - USB2.0 - 4 To) they seems good when I read the specifications
Everything has good specifications, but not everything works equally well.
The problem I have is that when I edit my films I work fast. And when I edit I used to expand and redimension my timeline very quickly (shift Z and Z)... It is ALWAYS when I do this that FCP quit !!! And the fact is that it does not happen when I convert all my edited timeline to Prores 422 HD 1920x1080 to work with color and come back to FCP to work with motion etc... Strange isn't it ?
Since ProRes is about three times the file size of XDCAM, are you still sure that it is a problem caused by slow drives? Does it still happen if you move the XDCAM files onto your internal hard drive? Try turning thumbnails off.
FireWire does not operate at its rated speed. While a FireWire 400 drive has the potential to transfer data at up to 50 MB/second, it doesn't.
Gigabit ethernet doesn't transfer data at 1000 mbps, USB2 doesn't move at 480 mbps, your 3TB hard drive isn't, and your internet girlfriend is 2 sizes larger than she says she is. Everybody is describing theoretical specifications, whose actual implementations may not be as good.
So may be that is the reason I cannot work at the speed I used to work with the Imac i7... What do you think ?
I'd try working from the internal hard drive. With a 2 TB internal drive, there's enough space for hours and hours of footage. When a project is finished, it can be archived.
If you want to see few of my recent works :
www.youtube.com/ecoregroup
Looks good. I think a company with a 1 billion turnover good afford some more equipment for you
