I owned the P239 in 9mm and, although I haven't fired one chambered in .357 Sig, I would think that the recoil and muzzle flip would be pretty excessive and hamper a person's ability to fire rapid and accurate followup shots. M1911 was right, in my opinion. The bore axis on a Sig is higher than most other handguns. I even noticed the extra flip with my 239 even though it was only a 9mm. My Glock 19 is a totally different story, because the axis is so much lower. I can get off four or five shots with the same accuracy as I could do about three with that 239.
Have you fired that handgun chambered in that caliber? If not, I recommend that you do so prior to making the purchase. If you buy the gun and THEN find out you don't like it you're going to lose $30-40 or more if you sell it as a "used" gun. Better in my mind to make a trip or two to the range and find out what suits you first.
Good luck and good shooting!