I have my sfp9 for almost a year with more than 3000 round counts. No malfunction or jam so far. Very accurate.
The paddle magazine release can be a benefit. I don't need to move my grip (to reach the release button) and use my trigger finger to press the paddle. It takes some time to get used to it. But once it becomes your second nature, the mag release can be done very quickly. And the paddle prevents accidental mag release( when you support hand is over the button).
I use it in IDPA club matches and I love it. I've shot Glock 17, M&P9, FSN9, P320 and I still prefer the sfp9 (the p320 second).
And yes, the magazines are expensive.