Karl Egloff set the round trip speed record of 6h42m24s (4h56m ascent) via the Umbwe & Mweka Routes (as did Jornet), as reported here. Egloff has worked as a guide on Kilimanjaro and elsewhere. A detailed interview with Egloff is on Ian Corliss' "Talk Ultra" podcast (the interview begins about 28 min. into the podcast). The interview includes discussion of verification.
6h 42m 24s