Recommendations for a tonearm upgrade on a VPI Classic 4 turntable

You have a very good arm; I have the same and I'd be interested to know what it is that you do not like.  But can't argue with you if you have the money to spend.  IIWY though I might look at the Kuzma, a design that has proven itself over the years.

BUT, before you do that you might, if you haven't already, try the VPI dual pivot.  A bit of a contraption, but it does improve the arm in a couple of ways.  Even better with the ruby ball point.

Thank you for your responses!  I will check out the SME and the Kuzma as well.

melm: to answer your question, my biggest complaint about the JMW 3D unipivot is that the alignment is not stable, particularly azimuth.  I will carefully align the azimuth, play a couple records, and then recheck it and it will be good. But I come back three days later and it is off again and needs to be realigned.  Even when it is statically aligned, I'm not convinced that in a dynamic situation that it is not shifting back and forth ever so slightly.  I think that with a cartridge that is as sensitive to alignment as the DV XV-1S, this is not a good thing.  That being said, with a Denon 103R (a cartridge which I absolutely love) this is not as big of an issue.

Again, this is my first unipivot and maybe it is just my comfort with gimbaled tonearms that is the issue.  Perhaps if I grew up with unipivots I would love this arm.  The good news is that I can have my second armboard drilled and mount the unipivot with a different cartridge.  

Oh, I almost forgot...adjusting the counterweight on the JMW 3D unipivot is a serious PIA.  Just when I almost get it dialed in, I overshoot and have to start over.  I'm sure many of you think that I am crazy and that you have no problems, but honestly, for a tonearm that retails for over $2k, this should be trivial. I have used many other tonearms that had very simple and perfectly sonic solutions to adjusting the counterweight easily and effectively.  This was clearly an oversight on VPI's part.  

So, my plan is to remount the JMW 3D unipivot on my second armband and probably put a Denon 103R cartridge on it.  I think this will be a great combination. When properly aligned, the DV XV-1S can be brutally honest when it comes to finding imperfections in the pressing or the recording quality, where as the Denon 103R can be much more forgiving (sacrificing a bit of detail, of course). The idea of having both options available to me at any time is very appealing.

I can relate to your tonearm woes.  I switched from my Sota Sapphire vacuum table with an SAEC 407 tonearm and Dynavector 20X2 LOMC to a modified Oppo 205D CDP.  I have never second-guessed the decision.                          

@whitestix , bet your vinyl sounds like crap on that oppo.