To my experience, Steyr M9 has the lowest muzzle flip I have experienced with any 9 mm, of course compensated guns excluded. Low bore axis and strong grip angle help to get the sights much faster back to the target than with my HK USPC9, for example. Of course, less flip does not mean less recoil, that recoil just comes straight back to the hand. Contrary to what my countryman Tony says I agree with those who say polymer framed guns have less felt recoil. Emphasis is in the word FELT, because lighter gun of course suffers of higher recoil forces, but the polymer frame acts as a damper and softens the recoil force before it reaches the hand.
I have not compared M9 w/ P99 side by side (I sold P99 much before buying M9), but IMHO M9 is a better gun than P99. I also like the triangle/trapezoid sights, while I know some others don't like them at all. But, to every man his own, market economy is great because it is based on the freedom of choice (within some limits, of course).
I have read and heard critical comments about Steyrs M-series, and i'd say these have been teething problems quite similar to early production Walther P99s. Many of the first P99's had reliability problems when that gun was introduced, but the factory took them seriously and there are not many complaints any more. Some of the first Steyrs have also had reliability problems (not mine, I have been luckier w/ M9 than I was w/ P99 some years ago) and complaints about the trigger, but Steyr factory also took it seriously. Current Steyrs should have the problems fixed, and at least my M9, after free trigger upgrade, has a very nice trigger pull, actually better DAO (safe action) pull than many DA/SA guns have in SA.
Sox, if you want to make a fair comparison test you should compare Walther P99 to Steyr M-series of the same caliber. They are about the same size, weight and concealability. Comparing a Subcompact (Steyr S) to a Compact (P99) is not a fair fight.
Ossi