First off the tables are at two different prices points. The well tempered Versalex is one away from WT top player. I assume you would be buying that WT used and the VPI New?
I would suggest buying VPI used as well if you can setup a table. Used market comes with risks but is more bang for the buck. Risk can be mitigated with smart buying.
I personnel believe that you can't go wrong with either tables. Put this in context you are buying a really nice table no matter which direction you choose.
Honestly the WT and VPI are just different flavors. From my extensive exposure to VPI and small experience with WT I could be very happy with either.
VPI seems to have a wider sound stage and bigger sound. a More neutral sound and more forward. More bloom in the bass slightly rounded.
The well tempered seems to be warmer. More laid back in presentation. A more taut bass. It does have a very nice almost tube sound in the mids but probably not as accurate at the VPI,
They are both really nice. Just different flavors. People love both and a lot of people say WT best VPI tables. I didn't feel that way just thought they were different sounding tables.