Soundlabs are sublime, well to me. Everytime I hear them I leave amazed. That said, the 989 Quad is almost the equal of the Soundlab Ultimates to me, but they are different speakers, and have different strengths. The bass from the SL's is amazing.
All that said, I have never had any problem with the build quality of the Maggies. They can be upgraded with with a better speaker stands (Mye stands are the best I have seen), and those adept at it can upgrade the crossover network. But for $4500, I don't think anything touches them. After having seen some posts on the Eminent Tech speakers I did a test drive and was impressed. At their price point, but they are not Maggies, certainly not in the same league with the 3.6R as far as dynamics, range or coherency. IMHO.