I agree that there should not be imaging issues with the Harbeth speakers. I've heard several iterations of the 30s and they are all capable of good imaging. Proper placement of the speaker and the listener and proper treatment of the room should be a priority. Given the OP's high budget, it might still make sense to replace the Harbeths, but the first thing is diagnosing whether the speaker placement and room acoustics are the major concern.
I've heard the 30s run off some crazy expensive amps and they are certainly capable of sounding very good when driven by such amps. My local dealer loves to shock customers with how good some small and more modestly priced speakers can sound when driven by really good amps. He typically uses an LS3/5A variant (Falcon, ProAc, Harbeth, and the original Rogers) for such a demonstration. This dealer only sells tube electronics, so the choice is typically a tube amp from Synthesis Audio. He does not recommend such extrem price difference between the amp and speaker; this is just to show buyers that they cannot skimp on the amp and expect to get the most out of their system.
Among my favorite real world combinations with the Harbeth 30.2s that I have heard involved the use of Synthesis A40 (40wpc) and A100 (100wwpc) amplifiers. The sound is propulsive and lively and full with these amps.
