first re: RS&C I would guess that there is a slow move away from ANT+ requests to BT? I see more people now running with phones than with dedicated watches. Also Suunto (& possibly Polar) make watches that are BT only now. Even if most requests have historically been ANT+ I suspect that will change.
You could fake it with your novel metrics by pretending they are something else. My limited experience with BT devices suggests they allow alerts to be sent, although I guess that is the phone as a "central" device. I don't know if RS could do that e.g. Every few minutes summarise the data and send an alert. I think even the garmins allow BT alerts. Just pretend it as an SMS....very much depends on whether RS has hardware to act as a central device, or just a peripheral. "Text From Runscribe: your flight ratio is X". Or maybe a Twitter message.
You could do it properly and create a 'runscribe Object". There is a protocol for sending Objects in BT I think. Bit pointless though as no one could interpret one of them. I suppose you could make the specifications open to any developer of phone apps. In a similar way to how Wahoo have done with the RFLKT+. This works very well. It connects ANT+ devices and bridges them via BT to phone apps, whilst also sending a display back. I would say about half of iPhone apps have adopted it, although some in premium only. Depends really whether you think you can convince App developers to adopt it .
I can't think of anything else. It would be nice to get live stuff, but I can see it would be tricky. I like the idea of faking text messages.
ps. I've just bought an Arduino 101 that has integrated (peripheral) BTLE. I'm sick of unconsistent treadmill speeds and intend to bodge together a RS&C BT signal using it, a lunch box, a piece of chalk, an infrared-LED/diode pair (speed) and a microphone to pick up bangs from foot strikes (cadence). Might work. Might not. Will I be able to see live BT output from the Runscribe too?