Hi BLS,
On my SME IV.Vi arm it has upgraded internal wire, mfg by Magnan. Hard to say if it's great or not, but the IV.Vi does seem to be a bit better than the other SME arms save the 312s and the V (which the only differerance is dynamic balancing and Van den hul silver internal wire).
I have a buddy with the 312s, and his TT front end is killer. My guess is the arm, but way to many varibles.
RE: my Nagra VPS. It's only about 2-3 months old. and I LOVE IT. Holy cow did it bring fun back into my vinyl set up. I had a all BAT system, VKP10SE super pak, VK51SE, VK150SE's with Wilson Maxx 2 speakers currently. The Nagra floored me on the transparency, retrieval of stuff in space, and it is just seamless. Music flows and my toes tap. Jeff in his current review summed it up pretty well. For the money, I think it's a steal, you have to really get a Aesthetix Io to beat it, which is where I was headed. 2 tubes vs a pile plus the small footprint and low power usage/heat output. BAT had me really sold on fully balanced. I had it from the cartridge all the way to the speakers. The Nagra isn't balanced, but more dynamic, just as quiet, and frankly more like live unamplified music. This last aspect, is by far it's strong suit. If you hear a cymbal live, that's what it sounds like. Ditto anything else...
My next step is a Nagra PL L or a BAT VK52SE. The Nagra equipment really draws you in, has no real flaws, very easy to own (low tube cost, low heat, low power) and sound just killer.
I am considering upgrading arms, maybe the new Grahan Phantom II or a triplanar. I just thought tweaking the leads on my SME IV.Vi couldn't hurt....