If you want more battery life and better smoothness, i would recommend to you to stay on latest SlimKat, (which is also currently i'm using). But if you want more features and colorfulness, maybe PA will make you love your device more (dont forget Xposed modules can grant you almost every feature). You wont lose anything by giving this ROM a shot. Most people agree on PA is one the best ROMs here. My suggestion is, watch the PA videos on youtube (etc. PA 4.4.4 xperia z1 review). You can decide without flashing and doing more stuff but just watching videos if you want to save time, otherwise, experiencing yourself is the best.