If we could trade Horford with picks and young players and get back Sabonis, I would do that trade in about a second. I am not the least bit worried about how Sabonis would fit with RWill or Tatum or anyone. He is exactly what we need and the fit would work itself out just fine.
In reality though, I don't see Horford plus picks coming even close to being enough to get the deal done. More realistic is RWill + Smart being involved. I don't think it would be unreasonable for Indy to ask for Brown. At that cost, I probably don't do it.
Sabonis is an all star level player. He probably won't be an all star this season but he is plenty good. I put him on a similar tier as Brown although I like Brown a little better head to head. He is a legit big and that has value in the NBA. What Sabonis can do is more rare than what Brown can do.