TLDR: Yes the SHV is a worthy upgrade from the VX-3. Especially if you plan to shoot further and dial turrets.
I have the SHV 5-20x56 on a .260. It's a great choice, reliable tracking and very sturdy. This year I dinged up the scope during a deer hunt. It was still ringing steel at 800 yards no problem. My only complaint is max FOV at 5X, but honestly I didn't buy this scope for 60 yard off-hand shots (which I had this year).
As far as glass, I've done direct comparisons to the Leupold VX-3 3.5-10x40, Leupold VX-6 4-24x52, Leupold VX-6 7-42x56, and the Swarovski X5 5-25x56. The X5 was the clear winner, but isn't even close to the same price range. The VX-6 glass is very comparable to the SHV. When compared to the VX-6 4-24, the SHV may have got me a few extra minutes at low light. The extra light could be due to the 56 vs 52 mm objective (we were testing all these scopes at the same magnification). Both showed significant chromatic aberration on a 500 yard target compared to the Swaro.
Recently I purchased a VX-6HD 2-12x42 for a lightweight 30-06. I haven't had a chance to do a side-by-side with the SHV, but I think the glass is better. To my eyes the VX-6HD has a nice warm hue, which I prefer in low light. The jury is still out on the new ZL2 turrets. I really like the way they work, I just haven't had a chance to test tracking.
For various reasons I plan to return or sale the VX-6HD 2-12. I may go with the VX-6HD 3-18 or VX-5HD 3-15. I'm also looking at the new Zeiss V6 and Sig Sauer Whiskey 5. I wish Swarovski had better reticle options and upgraded turrets for their Z5 and Z6 lines. I love Swaro glass, but the X5 is too big and heavy for this mountain rifle.