A little late, but here's my two cents.
I've played both the 889SG and the 989 extensively, and have played around with the new XO horns. The 989 is a solid, solid horn, especially considering the price. Intonation is good all the way around, nice mechanics and sound.
That said, I actually prefer the 889SG. The steerling silver neck this horn comes with makes all the difference. I felt this horn had more "pop" than its 900 series counterpart. Infact, I like this horn so much, I just bought one. Yes, I passed an 82Z, a 62II, an 875, an T-901, both the Series II and III horns and bought the Jupiter.
I would strongly encourage you can get both the 889SG and the 989 side by side