I just purchased a Tengu. When I was considering a saddle, the most important thing to me was comfort and quiet. I got both with the Tengu.
The Vi has more steel on it, steel tie-in, steel side d's (although smaller than the other NT saddles) and also brass swivel clips. The Tengu has an additional gear loop on the dorsal pad, where the Vi has a smaller biner loop.
As far as leg pads - all NT saddles, except for the basic and kids, come with the extended leg pads.
Not sure about the reason for the difference in leg pad spacing, but the Vi was designed by/for a woman. Not sure if that has anything to do with it or not. After hanging in the Tengu for a while, I actually liked the way the leg pad straps sat across my butt. I've had rescue harnesses on which the straps were so far apart that you felt like you were going to fall through them - They would ride almost on your hips and side of your thighs - kinda got in the way sometimes.
As for SRT - that's how I was trained - I like the extra gear loop in the back of the Tengu for hanging gear on. Advise: Get the pear screw_link_ option on the Tengu. I didn't and had to upgrade - there is little room for extra biners on the delta _link_ when rigging ascenders, prussics, and an 8, etc. Also, I always use a side pouch for ascenders etc. and the Tengu accomodates those beautifully as well.
What ever saddle you choose from NT, I'm sure you will not be disappointed. High quality stuff.
If you have further questions, call New Tribe. I did before purchasing my saddle, and they were great to talk to - very helpful and truly interested in getting me the right saddle for my purpose - fast service too.
Check out the reviews at
http://www.treeclimbing.com/content/blogcategory/35/108/Happy climbing -
Baker