I've had the almost identical problem, and have run the gamut of electrics over the years. I actually prefer a foil for speed and precision - and the Series 9 in my opinion is Braun's best - but I found the rotary Norelcos give me the least irritating shave regarding ingrown hairs. I would add that the most recent Norelcos with the "frosted" rings (S9000 Prestige, 7000 Series) seem to be the most effective at this, and it really does take about a month to adapt to a rotary. I also use scuttle, brush and lather, full up just like a DE shave. Just like a DE, equipment and technique matter for your individual shave, and if you've reached the pinnacle with the Series 9, shave on. I just found that a rotary reduced my rate of ingrown hairs with continued use, my theory being because of the way a rotary cuts - leaving the tip of the hair shaft rounded and "even" as opposed to the clean, sharp cut of a foil (or a DE blade, actually). And of course, YMMV.