Do you want this because it`s DSP? Or because its "Focusrite EQ`s and Compressors"?
First of all, the liquidmix doesn not include any of the good expencive Focusrite plug-ins like D2/D3. It only includes new plugs that emulate other "famous vintage" stuff. No telling if these sound good or what, at that price for that many plugs, I´m betting thery OK, but nothing to "write home about."
So unless the plug-ins are really just the way you want the, you are paying for a dedicated dsp for those plugs, and those alone. If you don`t use them, you won`t be needing the hardware either. So before spending 1000$+++ on changing your whole DAW set-up, why not see if you actually want the plugs included with the liquidmix.
Third.
Firewire DSP`s will induce delay nomatter what kind of DAW you are using, the only difference is that logic and Cubase has Automatic Delay compensation, while in ProTools LE, you have to fix this manually. So you can easily get by the delay in PT aswell.
If you want good EQ`s / Compressors, there are alot of other cpu friendly alternatives out there, like Stephen Massey`s plugs at
www.smassey.com and a good list of free /cheap RTAS at macmusic.org.
Massey plugs are being hailed as some of the best in the biz over at gearslutz and other forums. And they only cost 89$ a pop for fullversions.
However, if you really want the Focusrite box, than there is probably nothing else to do but buy the liquid mix. just make shure you actually WANT the plugs first.
Good Luck