  Compact binary millisecond pulsars with main-sequence donors, often referred
to as "redbacks", constitute the long-sought link between low-mass X-ray
binaries and millisecond radio pulsars, and offer a unique probe of the
interaction between pulsar winds and accretion flows. We present a systematic
study of eight nearby redbacks, using more than 100 observations obtained with
Swift's X-ray Telescope. We distinguish between three main states: pulsar, disk
and outburst states. We find X-ray mode switching in the disk state of PSR
J1023+0038 and XSS J12270-4859, similar to what was found in the other redback
which showed evidence for accretion: rapid, recurrent changes in X-ray
luminosity (0.5-10 keV, L$_\mathrm{X}$), between [6-9]$\times$10$^{32}$ erg
s$^{-1}$ (disk-passive state) and [3-5]$\times$10$^{33}$ erg s$^{-1}$
(disk-active state). This strongly suggests that mode switching $-$which has
not been observed in quiescent low-mass X-ray binaries$-$ is universal among
redback millisecond pulsars in the disk state. We briefly explore the
implications for accretion disk truncation, and find that the inferred
magnetospheric radius in the disk state of PSR J1023+0038 and XSS J12270-4859
lies outside the light cylinder. Finally, we note that all three redbacks which
have developed accretion disks have relatively high L$_\mathrm{X}$ in the
pulsar state ($>$10$^{32}$ erg s$^{-1}$).
