I'm not the person you replied to, but I was on 350 mg (which is a reasonably high dose). I was on venlafaxine regular release, not the extended release. If I missed a dose I got full on discontinuation effects. When I tapered off it wasn't great, but it wasn't awful.
Some people do report problems even with a very gentle long taper down.
Some people do report problems even with a very gentle long taper down.