REM Firefire 800 or Metric Halo Mobile I/O 2882

Hi,

I am in the process of pulling together a digital studio running pro
tools on a Macbook Pro.
I have a lot of analogue nice pre amps and want to still use them as
the heart of the studio but want to get them into the digital realm as
transparently as possible.
I also need the D/A to be as portable as possible as I do a lot of
location recordings.
I have narrowed it down to two products; REM Firefire 800 or Metric
Halo Mobile I/O 2882 but can't decide which to buy.
Any thoughts, suggestions and experiences would be really
appreciated.

Regards

Alan
.