I have auditioned the Sound Labs many times and have owned the Maggies. The SLs have lots more resolution and IMO are not as tweaky in their room placement, toe-in, etc. The Sound Labs throw an enormous sound stage with good tube gear and the HF can be tuned to your preference, adjustable on the back transformer. The SLs have just 1 panel where the Maggies have 3, thus the SLs cannot be bi-wired. The SLs I listened to also included a Tara Air power cord and a Richard Gray power filter on each, extra items not needed for the Maggies.
That said, a properly set up pair of Maggies with a large power amp can provide a great listening experience for a fraction of the cost of a pair of SLs.
That said, a properly set up pair of Maggies with a large power amp can provide a great listening experience for a fraction of the cost of a pair of SLs.