cdma v. no cdma

Apparently, there will be two models of iPhone 4s (am I right?): with cdma support and without. Unlocked iPhones will not support cdma, so I woun't be able to use them with Verizon or Sprint. Evidence of this could be found in the notes about unlocked phone and technical specifications on the apple web-page. Guys on the phone and in the chat were unable to give me a decent answer.

So I could either take the contract with Verizon and have an iPhone with 2 antennaes or wait for the unlocked one. The verizon one will later be able to work with cdma networks, such as Sprint and Verizon, whereas with the unlocked one these options will be closed for me. I will also be travelling arounf the globe, and (probably?) will encounter some other networks that are cdma and not gsm.

So, all other considerations aside, it seems better to buy the verizon phone, because it gives more flexibility afterwards.

However. My question is: what are the drawbacks of having the cdma option? Maybe the antennae will be weaker? Or it will eat up battery faster? Or the signal will be weaker? I mean, there's got to be a reason for not producing all phones with two antennae.

Would appreciate your insights,

G.