Danny Granger was 6'9" in shoes with a 7'1" wingspan. Risacher is 6'10" in shoes with a negative wingspan - 6'9.5". good luck finding a flattering comparison for risacher who has a negative WS on their in shoes measurement - there simply aren't very many out there. Also, while Granger was nothing special as a vertical athlete, he was quite a bit better than Risacher's 25" standing vert and 31" max vert. Risacher's combination of lack of length and athleticism is such that it is really hard to find flattering comparisons for him because those guys struggle to compete in the league. period.
I'm pretty sure Lauri has a negative wingspan to his height in shoes, but even more than Risacher. Risacher is basically even, it's not really a concern.
The way I see it wingspan helps you see potential for perimeter defense and 6'8"+ is fine. Risacher was a good defender, so I'm not really concerned.