I am at the other extreme: 133" diagonal screen from 12 ft away. HUGE difference between satellite TV and my A-20. I can even see a noticeable difference between satellite HDTV and my A20. Big improvement overall. I love my Toshiba HD-A20.
However, HDTV is meant to significantly increase the ratio between the size of the screen and the viewing distance. I suppose that your 46" is HD-compliant but, I am afraid to say, viewing it from 13 ft away cancels out any of the advantages of the higher resolution. In my opinion, it is, in fact, a waste of money.
If I were you, I would stick with the A20 (or replace it with the A2, if you feel that the A20 is too expensive) and add a few seats closer to the TV. No need to always watch HDTV from the bed. Also, please ensure that you have all the settings on your TV properly adjusted.