Very nice flying plane. You will be very happy with it.
I flew one for a few Months in Pattern competitions when I started (about 2 years ago). I wanted to fly Pattern but didn't have a plane, so a friend loaned it to me

and I am grateful (have sinced moved on to 2M planes, but have great memories of the Epsilon).
It has a OS 120AX fitted and has awesome power. A 91FX will be ample for Pattern. If you decide you want more power, the 120 will bolt straight in with no modification.
PS. the plane is still flying today