I have a Kannad Integra installed in my Discus CS. The fiberglass fuselage does not require an antenna of any sort in addition to the built in antenna in the unit. It works fine, I have tested it. It's an easy install and good insurance. Installation of the remote panel controls is a good idea, and also not particularly difficult.

I also have a SPOT attached to my parachute harness. I use it mostly for live tracking but it's a good backup.

I personally do not understand why people would choose a PLB over a properly installed ELT. Modern ELT work very well and are automatically activated. Assuming that you are gong to be conscious after a crash hard enough to set off an ELT is not valid in my opinion. If you are conscious, then great, manually set off your SPOT/InReach and your ELT as well!