I have a six speed and have experienced the stiffness in 1/2 in the winter but as mentioned that goes away once operating temperatures are met. Mine jumped out of first once on me and it sounded rough, whole Jeep jumped but only the one time so far.
I think if you do end up getting one and experience troubles the dealership you buy from can make all the difference. Find one you can trust and they'll go to bat for you if you have issues. Mine helped me a lot just to get me into the Wrangler so I know they will help me if mine starts having issues. Hopefully it won't since that's why I traded my Patriot in. I'm hoping Jeep doesn't give me two lemon's in a row.
2010 Flame Red Wrangler Sport - 4 Dr, 6spd Manual, 3.73 Gearing, Tow Package, Power Group, Dual Top, Black Appearance Group, Infinity Speaker Upgrade, Slate Grey Interior, A/C