Differences between VPI Prime and Aries 2

I'd keep the Aries and see about upgrading the platter to a Classic / Prime platter or an Avenger platter.  Might need some spacers under the arm and maybe a SDS (or similar) to adjust the platter speed.

The primary differences are the aluminum platter, a $1000 upgrade to Aries, and the 3-D printed arm, $1800 (10" arm)  upgrade to Aries.  If you want to do either of those two upgrades then it may be worth it to go with the Prime.  Now if you have the extended Aries which uses the 12" arm then you can't make a direct comparison since the 12" arm will not fit on the Prime, at least without looking very odd.  

Thanks for the comparison pmotz - that's the information I was looking for.  I didn't realize the 3D tone arm & aluminum platter were that pricey - that puts things in perspective.

I've also learned that VPI's optional (~$1k) periphery "outer ring" clamp only works with the aluminum platter.  It will not fit the acrylic platter on the Aries.   

You are asking a good question. I have a VPI Aries 2 Black Knight, but I've switched to the 10.5i Classic 3 tonearm, and it looks fine IMO.  The VPI 12 inch arm would look sort of odd to some in a rig like mine, given the proportions of the Aries standard (not extended).  I noticed an improvement with the 10.5i arm in terms of detail and soundstage, but also with bass response. Also am using the SDS speed controller, which I consider essential.  If I could find a VPI heavy platter, I might try that as well one of these days.

The Prime looks very nice, though, with its updated styling, and it might be the sweet spot in the VPI line-up.