Installing Trane furnace and need advice

Hi,

Looking for advice.

I am installing new combo, furnace Trane S9X2 and ac Trane X13. And I am thinking to upgrade the furnace to S9V2.

There seem to be a lot of conflicting info out there.

Some say there is real benefit in having S9V2, some say there is none.
For example the salesman I was dealing with said I will not see any difference if I get S9V2 over S9X2 just extra $$.

Would there be any real loss/benefit/advantage getting Trane S9V2 over S9X2?

I know one has variable motor and the other has I think 9 speed fixed.

Also, if I decided to go with variable S9V2, will my Nest second gen compatible with the system?

Thanks,
Gena

source https://hvac-talk.com/vbb/showthread.php?2223669-Installing-Trane-furnace-and-need-advice&goto=newpost