I think from now on I'm going to add pads and traces for a Splatch to everything that's experimental. In the (unlikely) event it doesn't cut the mustard, I'll just un-install and solder a regular wire antenna directly to the RFM69. In this manner, the option will exist to utilize it if desired, and along the way I'll collect datapoints on where it's effective and where it isn't. The added PCB board real estate to accommodate its pads is small.