If you are seriously considering a Metric Halo device I suggest you go to the user's forum - link at
http://www.mhlabs.com and read for yourself. Reserach "digital i/o"..."ADAT grunge" etc
You will get good AD/DA quality. You may not be able to get any digi i/o functionality at all. Some do - others don't. Only one person that I know of was able to maintain digital sync for more than 10-15 minutes. Some can't get it at all. Higher SRs and 24 bit also would appear to be more problematic than 16 bit 44.1 Apparently it has to do with the rest of the gear in the setup, but obviously MH devices do not have very strong stabile and predictable digital i/o functionality. Metric Halo will not tell you this - it is up to each user to figure out for themselves after purchase.
I figured out what was going on by reading thru the archive and asking questions. There turned out to me a mini-flood of "me too" posts that came back, with a reasonable amount of irritation at the situation.
Further - because MH is completely dependent upon the energy and well being of one person w/re to software/firmware etc - that is BJ - and they have so many fences to scale just to keep up with OSX and their newly released DSP functionality - it would appear as though this digital i/o problem - which has been present since the EM review in 2002 - is low on the priority list.
If you only want to get great recordings thru the AD - i.e. a chamber group or small ensemble - it is great. If you want to use it as the hub of a digital studio......all I can say is dig thru the archive and decide for yourself.