Hey Nature,
I have a Van den hul Frog with the Extreme Tempest.  Sounds fucking great.  I also have a 'standard' Tempest - have not tried the Frog with the unit, I upgraded the other Tempest as part of the cart upgrade plan.  My 'guess' is huge difference between the two Tempest models w/respect to analog.  If you are considering a similar output cart, I could do an A/B between the units.  Again, I am certain the Ex does a better job.  Let me know - access to swap the units is not too bad.
Don