There is just no reason, IMO, to buy into the ancient external DSP platform. It's one hell of an inconvenient and under-powered dongle.
uad2 plugins to my ears are very very good sounding, they never really sound exactly like the hardware, but i think nobody here has the money to a/b the fairchild against the uad clone

so yeah : uad cards and shark dsp is outdated, but the main difference between dsp and standard cpu is : dsp work in realtime.
if we ran the uad plugins on our cpu, i think we would end up with 10 seconds of latency, which would suck balls.
im only guessing here, maybe im totally wrong?
but the main aspect is : without the uad card you cant have the uad plugins. i hate that everyone owns waves plugins, ozone etc. because there is just no safe way to protect their software. uad have walked the right path economically. i like the idea that not every kid has the uad plugins available in his "home studio".
the sound : i love my uad plugins, but at the same time on every prroject i run into major dsp power problems... i will have to spend another 1500 on a quad just to be able to run a massive passive AND 4 fatsos... that is infact outdated especially considering the price you pay for uad cards.