Yes, globular clusters are expected to be prime locations for BH-BH mergers and gravitational wave events. The few GW detections we now have put some bounds on

Yes, globular clusters are expected to be prime locations for BH-BH mergers and gravitational wave events. The few GW detections we now have put some bounds on the BH-BH merger rate, but as far as I know, those bounds are consistent with the rates needed for IMBH formation.