Hi
firstly I'll say that speak to two surgeons (both with solid histories of good outcomes) and you may just find you have two opinions which are quite far apart. After you ask about 50 I reckon you'll start to see a scatter plot showing quite an amount of overlap.
Watch this video of a conference where a panel of surgeons discusses their work
https://www.youtube.com/watch?v=_iVVmBgWsiE&t=64s
you'll see some variance of opinion (each defending their own)
I can see the logic both ways. An important factor is to reduce time in surgery and reduce time on the heart lung bypass.
If you replace the valve you run the risk of damaging the AV node which is right beside that (meaning "hello pacemaker"), but (assuming you don't) you can then install a device which has the graft pre-attached at the factory and will reduce operation time and (if you've done any plumbing around the house) reduce the likelihood of leaks around that join (search on paravalvular leaks).
But if you leave the valve and attach a graft to the existing valve seat you need to be sure that you can securely attach the graft to the remaining tissue (which will likely no longer be in perfect condition due to previous surgeries, scar tissue ... bla bla bla ... you get the picture.
I'm not sure I'd believe that a Surgeon would say that ... are you sure you're not paraphrasing and perhaps misunderstanding his meaning?
As to the issue of the lower INR, I sit with Superman here in that to me it is nothing more than a marketing ploy. I have not seen even a single claim from the maker that all it does is "reduce bleeds". I see many studies (would you like me to post a few) that suggest that a well controlled INR between 2 and 3 has few bleed complications.
One must be clear that as you age the "risk" of a bleed increases for everyone, yes even for people who have never taken warfarin. They make no claims of other "benefits" of reduced warfarin (and to be frank in well over 50 years of usage history among millions of people warfarin isn't strongly linked to any specific problems anyway).
To me its a teddy bear for those who've been led to believe its a problem (when actually all the evidence points to clinics being the problem)