I own the Tascam and I'm also using it with Cubase (SL3). It's a nice unit for a hobbyist like me, but there are some issues that are bugging me:
- Tascam driver update policy
- driver instability
- the Mackie HU emulation doesn't really work out of the box. For example, I can't use the console EQs in Cubase because the EQs are controlled by the pan knobs (!) (probably there's a way to re-program it, but that's not how you want to spend your weekends).
I got it second hand for a good price, and since I'm just recording for my private pleasure it works well for me. The preamps sound good to me (compared to the USB-interface I had before), but I can't compare it to another preamp of this price range.
The display of the M-Audio will definitely be a plus.
You could consider buying a good stand-alone interface (RME, Presonus etc.) and additionally a controlling unit like the Mackie Control or even a simple Behringer one. (I found out that I basically use just the faders and the transport functions on the Tascam and still do most of the work with the mouse within Cubase. But then again, I'm just a hobbyist.). I think, that's the way I'd go today.