I use SF only for mastering and for edit of single tracks.
To edit multitracks you need an interface and software that will read and edit your Tascam.
This all gets complicated, and I have done it before using 3 ADAT's, motu 2406 and cakewalk and Sound Forge .
But I use a PC and not a MAC so motue kept crashing things.
I now use only the PC with scsi hard drives, sonic foundry vegas, sound forge, cd architect, and some others.
I have all compatable software and use a Delta 1010 for D/A and A/D.
I also still use external gear and a mixer as there are some things that the PC software cant sound like like a good lexicon.
My system does more than will I need, and never crashes.
I guess to conclude, if you want total controle over recording and editing, build a PC or MAC and do everything from there.
Dedicated Recorders are great if you dont want to take the time to learn how to use a PC, or for recoeding live multitracks but, you will always be limited in what you can do ;-)