Having a 3G/4G model also affords you flexibility at a price. If you're ever in need of a data plan for whatever reason, including while traveling overseas, you can just buy yourself some access. For security's sake, I'd suggest reading up on the risks of using public wifi, which can expose your data to unsavory types. You can find lots of info by googling a phrase like "public wifi risks." Whether it's your email, social networking accounts, financial info or whatever, you should know the risks and decide whether you want to take them. For me, the choice is easy; I'd rather skip access than use public networks if I couldn't afford a data plan. YMMV.
If you use public wifi, VPN is a security possibility worth considering, also at a cost.