Design style and when to use interrupts

In my next project I'll be using low cost radio units ($12 for transmitter and receiver, 150m range) driven from an Arduino with Holtek HT12D decoders (8 bit unit address, 4 data bits) to send handfuls of bits to various locations. I've implemented the encoder function in software to avoid the chip and consuming 12 digital pins, but there is a decision to be made before I turn this into a general purpose library.

Sending the code with sufficient redundancy and enough data to sync the radios takes around 100ms. I currently do this in a synchronous routine with is fine for in this application, but I wonder if it wouldn't be better to implement this with timers and interrupts to have a lower impact on timing sensitive clients. On the other hand, is consuming a timer and inhabiting the scarce interrupt level more disruptive to a client program?

Opinions?