Hi Rob,

Yes, that would be about the size of it.
the L variety are pretty small... 4 together are still smaller than a conventional 4 way opto-isolator, If you pack them neatly enough you can probably fit 5 in the space of a 4 way opto.
They are amazingly good at handling transients and spikes aswell as they can inherently operate at up to around 30volts.
They fail safe generally aswell, ie if the input voltage exceeds the limit the output generally clamps to zero (ish) thus no damage is passed onto the PIC.

It may not be suitable for your application, Its just another thought in the melting pot.

My units are fitted externally to a vehichle in all weathers and Ive had non returned as faulty to date so they are relatively robust.

I believe they have even attached them to 24v vehicles with no changes to the circuit and still they are super reliable.

Hope this helps

Regards

Darryl...