well considering that the mackie hasent even shipped yet, there are very few people who have used it. I've heard bad and good things from the people whp have had the opportunity to use it, the tascam is shipping, and have heard good and bad things about that..but for the most part it looks to be doing what tascam said it would.
as far as a computer goes, thats where the mackie has an advantage. with it (well what the literaute says anyway) you can plug in you mouse, key, and monitor, and start editing. with the tascam, yuo have to have a computer to visually control the editing. the tascam machine and the computer talk through an ethernet connection. that being said, I would still go with the tascam, thats a very small selling point to me..you may have different needs, so being able to edit without use of a computer might appeal to you more.
ametth