Personally, most 8 strings I've heard don't sound as full as a well made Spruce Top Tenor strung low G. In fact, most of them tend to sound twangy, for lack of a better term.
If you think about it, an 8 string's lowest string is a low G, paired with a high G, the mid C is paired with a high C, the E is doubled, and then you have a double high A. Lots of high strings in that tuning.
Depending on who's playing, most Lili`u 6's have more balance, but still range towards the high side. I like how John Kitakis sets up his 6 - Low G, Octave C, E, double high A. On paper, this may sound twangy with the octave C and double high A, but the low G is the key. I did something a little different - Octave G, double high A (basically an 8 minus the extra strings on the 2nd and 3rd). Strung either way, they make for a very pick and strum easy instrument.
Then again, listen to Peter Moon pick his Tiple (my friend does the same).