The USB stick looks a lot like a rebranded Hauppauge
WinTV-HVR-950Q which I am testing for quite some time extensively. So far, I am not impressed - quite the contradictory to be honest.
If you are planning to use analog television, I would definitely get the Plus as you have no idea how much power a PC needs to do real-time MPEG-2 encoding at a decent bitrate and decoding at the same time for doing timeshifting for example. With a hardware encoder card, you can do timeshifting even on a low-grade Celeron or Turion, while with a software encoder you need a dual core machine and still have like 60% CPU usage.
For ATSC, it doesn't make a difference which of the two you choose since ATSC comes encoded anyways. When you record something, the program will most likely simply write the MPEG transport stream to HDD without doing any post-processing. For ATSC SDTV, a PC that can play back a DVD is most likely suitable for watching TV as well.
One more thing - if the Hybrid really is a 950Q, I can tell you that that thing gets HOT!