FWIW- I now have 1/2" 8 track and a 1/2" 16 track. The 1/2" 16 has the same track width as a 1/4" 8. Its a Tascam msr-16.
Only had the msr-16 for a few days, but my initial observations are:
1) With dbx NR engaged, there isn't a stunning difference in the sound of the two machines. Wihtout noise redux, the 1/2" 8 does sound better. I'd say noise redux is a must for a 1/4" 8.
2) If you're already acustomed to the convenience of digital recording, having only 8 tracks is kind of a shock. Its a good shock, though, and gets you thinking a bit more creatively.
3) With NR, there is a difference in sound with the 7.5 (low) and 15 (high) speed settings on the 16 track. Its nice to have the option- low to save on tape and high for better quality. Or just to have to different sounding options. Slower doesn't sound worse, just a different EQ curve to take into account. I don't know if the 1/4" 8's have variable speeds, but it kicks butt.
4) A 3 head machine will give you the option of getting tape saturation directly into your daw if you have the hardware I/O for it. Send a track out to the tape deck, record it, run the play head output back into the DAW. Depending on your software you'll have to account for the delay, but its not hard. Can't be done with a 2 head machine that I know of.
Anyway, I'm really happy I have a couple digital and analog options now. And I *strongly* second evm's warning that its addictive.
Take care,
Chris