I wouldn't say small, since the display is a bit brighter and faster, smaller notch, slightly bigger battery, matte finishing on the back, and 2 extra cameras. haha. It's a bigger jump than the 6T to 7 i think.
But then depending on your needs, those are probably not worth it to sell OP7 to get 7T.
For me 90Hz is nice to have, but not must have. To me display quality and brightness is more important. For example, if i'm looking at instagram, the photos looking nicer is more important than the scrolling looking smoother to me. Also there are so many other things on a phone that I would prioritise over a screen with a faster refresh rate too. Like battery life, camera performance, speakers, etc.