Transparent vs. API mode

When in transparent (AT) mode, do the XBee modules do anything to ensure that packets aren’t dropped? Or is that only possible if you use API mode and ensure that each packet you send is received correctly by looking for an acknowledgement?

I am using two XBee Pro Series 2 modules to transfer some data in AT mode. Sometimes the data comes through fine, but other times it is corrupted, or things that were sent on one end are not received on the other. Is this to be expected, what is the best approach to ensuring that there are no dropped packets? I presume it requires using API mode, but perhaps not?

The data I am trying to send is a set of measurements which total 24 bytes and are being measured every 10ms (100hZ). I don’t need to act on the data in realtime, but I do want to make the most effective use of the XBee and minimize packet drops. How frequently should I be sending packets data wirelessly? Should I try to transmit each set of 24 bytes as its own packet, or is it generally better to maximize the payload?