I'll second not trusting a shared link for STL. I run a wireless isp and I dont even trust my network for mission critical data such as on air audio unless I build out the customer a dedicated wireless path with no other traffic on it.
With that said, the stations I consult for have a t1 circuit at one site, bridging ethernet over it with cisco 2610 routers, we're using it for STL as well as a return path for RPU, also for a surveillance camera at the site as there have been some issues out there, finally we're sending RDS data to the encoder over it. Using comrex BRIC Link for audio over IP, has been a great pair of devices, set them up and forget they even exist as long as they're on a good circuit.
I'm using some barix boxes on a wireless link for an AM, they work pretty well but are not as tolerant of connection faults as the comrex units. I also just recently had a barix hardware failure, luckily I had a spare encoder on hand.
the wireless link there has been good, tranzeo tr-902 on stl antennae so in a pinch I can throw the old marti stl-8 on and keep going. again, using the connection for more than just audio.