well, even the most expensive PT rig has 24 bit internal processing, even sonar has 32 bit floating point.
The RME just sounds amazing, and their technical know how is unmatched, they invented a way to get ADAT Lightpipe to work at 96KHz, the sound is the deciding factor though, just beautiful sound, PT has this weird boost in the high mids and the bass is kinda flat and lifeless. Anything run in PT has this weird character of no character, that's why the pro's don't mix in PT, they take the individual tracks out through Apogees and run each into an SSL to get a good sound. That's over 100 grand just to avoid mixing down in PT. They avoid it because PT is probably the worst as far as summing algorhythms go, many logic, nuendo steinberg users don't take it that far because their summing is much better, but not analog summing better, but much more passable.
Also, Digidesign puts booby traps in their drivers so as to encourage you to use PT and to upgrade to their most expensive stuff, I know many people who have tried to use logic with PT hardware on macs, and at first it works, then in starts getting glitches, then you get audio drop outs. This happens over a few weeks, but then you use PT and everything is dandy.
Logic tried to address it but it is something built in to the PT driver, not just sloppy code, but a boobytrap to boost their rep and pull a tanya harding on the competition. But Apple got them one better, the new version of OS X is supposed to send Digi back to the drawing board where they will have to rewrite their driver to pass the apple test, since the OS will be a new rewritem apple don't play that shyt.
Also, on a dual 2 ghz G5, the digi002 driver had clogged up 50% of the processing power for no reason. Removed the Digi002, used RME, wow, together they use less than 10% of the power when running mad tracks.
Sabotage man, they play really dirty, even some of the reps have admitted that these things are put in intentionally, saying "well, they want you to upgrade to the HD"
sheisty.