Pressure assist toilets were a gimmick some manufactures came up with in an attempt to make there poorly designed toilets work with the new low flow requirements. The are very noisy and prone to fail. Kohler is not known now days for a quality toilet. They keep coming out with new models, but they still clog frequently. More over, their redesigns use parts that only Kohler makes and in some cases cost as much as some toilets. I understand why you will stay with Kohler, and I wish you luck. Maybe this 6th design will work, but I'd keep a plunger handy.