  We perform two-dimensional particle-in-cell simulations of magnetic
reconnection for various strengths of the guide field (perpendicular to the
reversing field), in magnetically-dominated electron-positron plasmas. Magnetic
reconnection under such conditions could operate in accretion disk coronae
around black holes. There, it has been suggested that the trans-relativistic
bulk motions of reconnection plasmoids containing inverse-Compton-cooled
electrons could Compton-upscatter soft photons to produce the observed
non-thermal hard X-rays. Our simulations are performed for magnetizations $3
\leq \sigma \leq 40$ (defined as the ratio of enthalpy density of the reversing
field to plasma enthalpy density) and guide field strengths $0 \leq B_{\rm
g}/B_0 \leq 1$ (normalized to the reversing field strength $B_0$). We find that
the mean bulk energy of the reconnected plasma depends only weakly on the flow
magnetization but strongly on the guide field strength -- with $B_{\rm g}/B_0 =
1$ yielding a mean bulk energy twice smaller than $B_{\rm g}/B_0 = 0$.
Similarly, the dispersion of bulk motions around the mean -- a signature of
stochasticity in the plasmoid chain's motions -- is weakly dependent on
magnetization (for $\sigma \gtrsim 10$) but strongly dependent on the guide
field strength -- dropping by more than a factor of two from $B_{\rm g}/B_0 =
0$ to $B_{\rm g}/B_0 = 1$. In short, reconnection in strong guide fields
($B_{\rm g}/B_0 \sim 1$) leads to slower and more ordered plasmoid bulk motions
than its weak guide field ($B_{\rm g}/B_0 \sim 0$) counterpart.
