I think Love is a very poor comparison for Sully. Love is no athletic specimen but he blows Sully out of the water in the regard. Love has always been a proven shooter while Sully is a bricklayer from range.
I think best comps are Reggie Evans or Danny Fortson. Sully has VERY slow feet and will always need to play next to a long, quick type like Melo or KG to not be a complete defensive liability. BBD on the other hand has very quick feet to get around defenders and can finish at the rim creatively.
Sully cannot finish at the rim at this point. Al in his first SL was already beasting down low with creative finishes. Sully has been launching prayers this whole time.
BBIQ helps but not when you're heaving bricks or your shots are being shoved back down your throat..
As far as the slow feet and athleticism, it is tough to argue. Although I am excited to see what getting with an NBA trainer can do for Sully. He is never going to be fast, but I would not be surprised if he could be similar to Love (who got a lot quicker when he shed some extra weight).
Also, Sully still has work to do on his shooting, but he does have nice touch and a great release. I think right now he is working on extending his range, and with a little more work, he should be a very good shooter from distance.
I really think the comparisons to Evans and Fortson don't work though. Not only are those guys quicker than him, but he is MUCH more skilled. His shooting, passing, and BBIQ are all off the charts compared to those two.
Ultimately, I think the best comparison I have seen to Sully is Scola. Who is basically a slower Kevin Love.