My sister and father have both had this operation for both ears. While they are not divers my sister finds it near impossible now to equalise beyond 2-3m deep in a pool, and finds even more gradual changes in pressure (e.g. driving to altitude) uncomfortable.
Their doctor advised against SCUBA diving, bungee jumping, sky diving, flying with a cold and even avoiding head knocks. This was to avoid any dislodgement to the insert to replace the stapes, or damage to the ear drums. They were told that if dislodged then the insert could not be replaced resulting in permanent conductive hearing loss. The only option left would then be a cochlear implant.
I believe that for a dive medical here in Oz, a stapedotomy would result in failing the medical.